Sycraft
I clean mine out with a device that the students at work christened "Derpy Duster" after gluing googly eyes on it. It works well, just blast the dust out periodically. I recommend them highly.
 

I bought a fan duster for my computer a few years ago, and it turned out to be not much better than a hamster blowing through a soda straw, and I went back to the liquid "air" DustOff cans. My wimpy duster was based on a rechargeable battery, not the 500 Watts this item claims. Even an incredibly inefficient impeller should be able to generate some velocity with that power. At $60.00 this would be a cost effective replacement for canned dusters for anyone using them on a regular basis, if it is actually able to deliver equivalent volume/time into the same cramped spaces. The picture of blowing on a keyboard does not really match some of the applications you might want to use it for. Is it as effective as the cans?

Mesh: Do you mean per use or total? Per use it lasts as long as you like. Though it is perhaps not clear from the pics it is an electric vacuum (just has the intake and exhaust reversed form a normal vacuum) and runs on 120v line power. It goes until you turn it off. If you mean total life I can't say, we've never broken one. 10 years or so I'd imagine.
 
slartabartfast: WAY more effective than cans. With its large attachment, the long one you see sitting on the ground in the second picture (which looks like a big nose and earns it the derpy name) it has a higher pressure than the cans generate at their peak, and of course do so over a wider area. It's performance does not degrade as cans do when they get cold since it is just a blower. It maintains peak output 100% of the time. It is enough output that the smaller nozzle you see has an opening in the top to lower the pressure.

Thanks Sycraft.....yeah, I didn't realize there was a power line and thought it like a pressurized can or similar.
While we're on the topic and thinking out loud....wouldn't it be better to have small device like this that vacuums the dust/dirt from the case rather than blow it everywhere? (less of a mess to clean??)

I am a big fan of blowing the dust out. You will get much more dust out that way.  All the hidden dust a sucking vacuum does not get to is left behind.  I put the computer down sideways out on my driveway outside on a soft blanket.  You can see what looks like an explosion of dust that rises like a giant nuclear cloud.  With the light out there you can see what you are doing much better too.
 
It is important to stop all fans turning when getting in real close with the air. The air will make the fans turn at speeds far faster than normal.  It could damage them.  They are easy to restrain.  I remove fans from the computer chassis and clean both sides.  Much more dust comes out.  I use a very soft brush on the end of a long handle in conjunction with the air to clean the fan blades.  I also remove the CPU fan from the top of the CPU heatsink and give that all a great clean out too. Tons of dust gets jammed down inside the CPU heatsink itself.  Sucking may not even get to it or move it but power blowing certainly does.
 
You need the right tool for blowing.  Air compressors can be too strong and easily damage delicate internal components.  Reversed vacuums are often not strong enough.  I have found a great product here that is mains powered and had a range of attachments.  It blows normally but can be reversed to suck and it makes a fine vacuum too.  I use it more so for blowing air.  Because of the variable ends you can attach, the air flow can be varied too. On the end of a little hose too you can get into nooks and very tight areas I bet the large powered can type device may not.
 
http://www.godfreys.com.a..over-flow-blower-vacuum
 
The air flow can be pretty damn fast too when needed.  Fast and powerful enough to even clean out the dust that gets buried in your power supply and that gets full as well making it less efficient.  You don't have to take the power supply apart.  Just focus the air in through the various fan openings etc and it all comes out the other openings too. Sucking would never remove that internal power supply dust.
 
My computers always look pristine after cleaned out this way.  I made the investment in the machine because I have four towers that all take in various amounts of dust in various locations.  Synthesisers can get quite dusty inside too and this comes in handy for them as well.
 
My OP was not so much about improved CPU cooling as such.  Although the discussion on cooling CPU's always interests me a lot. After removing and cleaning the fan I was able to easily unclip the heatsink from the CPU core and that is when I noticed the poor thermal grease there. I cleaned and re applied some new stuff and as I said the CPU temp has taken quite a nose dive.  The dust in the heatsink would not have helped either if you think about it.  No air flow around the fins.  And the dust would warm up the heatsink as well.  Not cool.
 

I use a small paint compressor to de-dust computers. Obviously out-of-doors. And a basting brush to clean fans and heatsinks, if needed. Stiffer bristles than most paint brushes. And tooth brushes.
 
Got a giant ninja on the cpu with a 120mm fan.
 
And now no case fans.  After I read the Google research about drives living longer when allowed to run within the recommended temp range I stopped the front fans and tested.
 
A couple of months ago the rear 120mm fan started barking. I disconnected it and tested. All temps within range.
 
Currently running a 4 core phenom overclocked 25%. Never gets over 40 degrees. And a fanless dual head video card, and 3 disks.
 
 

Mesh
Thanks Sycraft.....yeah, I didn't realize there was a power line and thought it like a pressurized can or similar.
While we're on the topic and thinking out loud....wouldn't it be better to have small device like this that vacuums the dust/dirt from the case rather than blow it everywhere? (less of a mess to clean??)

On account of how pressure works in these situations, no. With a blower, you can get good movement on things even from some distance away. With a vacuum you have to be right next to it. Try it some day with your vacuum: Stick your hand near it and notice how close you have to get for any real suction, then compare that to a fan (or the vent on the vacuum). Blowers do a better job.
 
That said, I usually fire up the vacuum and/or a HEPA filter to grab all the dust that gets blown around.

Interesting... I've had my laptop for getting on four years now and I've never opened it up to check the dust levels... Perhaps I should...
 
edit:
 
Well, I did it. I found a youtube video showing how to get to the internals of my Clevo P150EM. It even showed how to remove the CPU and GPU heat sinks.
 
So I dived in and was amazed at how much dust was clogging up the heat sink fins. They's all had a nice brush down and blow out and everything looks much cleaner.
 
I had to nip out for some thermal compound because the original stuff was a bit cooked.
 
All back together now and the laptop turned on, so that's a bonus.
 
Only problem is, I don't think I can monitor the CPU/GPU temperatures anyway, so I'll never know if my spring clean made a difference. I'm just happy to got rid of the years of dust in there :)

CPU temps are usually monitored in the bios before you actually bootup into Windows. You need to get into your bios and you will find it in there. There are programs and free ones too that you can install under Windows and also get that info.
 
It would have been good to do a reading before and after your clean but at least once you do find you CPU temp, do some research and make sure it is within range and not at the high end of the range.
 
Sounds like you did some good there. You have got me thinking about my laptops now. I have never thought of opening them up at all!

Hi Jeff,
 
I went into my BIOS first, but it appears to be a very, very simple AMI BIOS and no function at all giving the processor temperatures. I'm wondering if that's because, being a laptop, temperature readings are not considered important. I'm just guessing, of course.
 
I'll have a further look online and see if I can find anything about my laptop model and if there are any third party programs available that give processor temps.
 
One thing I would say is, I played an hour or so on my favourite computer game, quite demanding of the CPU and GPU and I didn't encounter any of the issues I was experiencing prior to the "spring clean." 
 
cheers :)
 
andy

I use this tool for temps and checking drive health
http://www.almico.com/speedfan.php
 
The sensors are not always correctly identified.  I especially like it when HD is listed as -999.
 
I have had to replace fans in laptops. Not a pleasant task. Using the small paint sprayer compressorto blow through all the holes usually works. But I the fins can become clogged. And fans can be stopped by dust piles.
Mostly these problems occur from actually putting the computer on laps and other surfaces without using a hard surface between the computer bottom and the cloth. When not sitting a t a table I use a clipboard to elevate the openings, and to prevent sucking fibers.
 
This past week I disassembled a client's laptop. Looks like a bad MB. took at least 30 minutes to get the thing apart slowly, finding and noting all the connections, and fighting with some of the little dudes, and hidden screws.
 
I recommend to not disassemble unless you havta.