I have a desktop as my Daw, I'd like advice on laptop Specs to handle the work too?

Hi there from a very cold England!
 
I recently bought a Sony i7 2.1 Ghz 6 Gig ram 17 inch screen laptop for exactly the same reason you're looking!
Unfortunately the need/desire for 7200 rpm hard drive meant that the choice was already limited to a very few machines.
 
I took the 'DPC latency checker' on a stick to a local dealer and checked to see if they were ok before buying. If you haven't got it, Google it and you'll find it easily and it's free.
The PC latency was within limits (just).
After buying and after switching off (and disabling) wi-fi, and unloading all the preloaded and startup rubbish, it has latency of a few milliseconds on an Edirol UA101 outboard USB sound module.
With the onboard soundcard it is awful... and that is likely to be your problem.
 
There are countless threads here and elsewhere about that particular issue and I can only hope someone who has a working onboard card will let you know the set up they use. I doubt a dealer will let you load up your Sonar software and try before you buy!
 
Luckily for me... unplugging and taking the UA101 inside was not much hassle, so it works for me.
 
One important point you might need to consider is the operating system.
I had everything set up on XP 32 bit on the Desktop, but the laptop came with windows 7 64 bit.
There are a lot of issues with compatability which would fill an entire thread.
They can be overcome, but it took me almost 3 weeks of work to find the answers and then make the changes for plugins, drivers and the network. I will still need to install 'Jbridge' to use some of the 32 bit plugins!
I don't even bother using the Desktop for music any longer. The Sony will run dual monitors, so I use that on a TV indoors or plug in the desktop monitor in my office/studio!
 
One last point... the Sony was £300 cheaper at the dealer... but came 'downgraded' with a 5400 drive (but the same model number). Cheeky! I eventually bought the 'proper' version elsewhere.
 
Good luck.
 
 

Well I don't really plan t use it to actually record anything  I suppose a situation could come up that would make me want to pull that out to record a live gig or acoustic drums in a bigger room than mine or something like that.  So I guess that should be considered though otherwise for editing I wouldn't care much if there was a 1 sec. latency or more as long as the tracks play in-sync with one another!   

   My Daw is running Windows 7 and I am operating Sonar 8.5.3 Producer in 32 bit even though I have the 64 bit aswell  (From what I can tell, there doesn't seem to be any major difference in sound quality so I figured why bother limiting what plugs I can use?  Not all are available in 64 bit)
   My current interface is a M-audio fastrack pro which would be easy enough to carry inside and use there if need be as long as I have the right drivers in it.
   Food for thought!

Looks cool and it should for almost $1700.   Not sure I'll go that way though.  Thanks Zo.