robert_e_bone
http://www.howtogeek.com/howto/windows-vista/resize-a-partition-for-free-in-windows-vista/

 
Godsend.  \/
This and CCleaner and Disk Cleanup update altogether will probably keep me making music on this pc.
 
However...at the bottom of the page, it says, "Note that the extend partition feature only works with contiguous space."
I'm wondering, if I shrink D drive, which side of D drive will it create space, to the left or to the right? If it's to the right, dose it mean that I can't expand C drive because the space isn't contiguous? Or will I be able to move the space left and right?

John T
The Disk Cleanup update is in Win 7 too, but it's a bit weird to use. You have to run disk cleanup and go through the scan, and the Windows Update files initially won't show in the list. If you then click the button marked "Clean Up System Files" (requires admin privileges) it will do the scan again and add them to the list.

 
Thanks. It showed up in the list and was taking 792MB of my C drive. Deleted it. Good riddance!

A point worth noting about disk partitions: there's not really a benefit to partitioning a drive in most cases, apart from organisationally.

Lesson well learned. Thanks.

So I used CCleaner and it helped me a lot. Now my C partition's free space, which was only 1.5GB yesterday, is 10.6GB. Wow.
 
CCleaner taught me the major culprit was system restore files. There were nearly 10 files so I deleted most of them. It made a big change.
 
However, I'm starting to think of using an external hard drive for everything other than the OS and applications. After all, that's the recommended setup, isn't it? I currently use two external drives for backup pupose (one to keep in my house and the other to keep elsewhere), one of which is a reasonably-priced, compact HDD. So I'll probably get another reasonably-priced one and use these two for backup purpose, and format the high-priced one to use as a second drive, then I'll be able to delete the D and E partitions and use the whole 320GB (smaller than that in reality) for C drive. I've never recorded anything directly into an external drive, so I don't know if it's going to work as expected, though.
 
Anyway, thank you all so much for helping me. It was a very informative thread. I hope it will help others who are as ignorant as I was.
 
And...yes, I'm ready for X3d now. 

I've got a dinosaur system and record to an external drive exclusively.   I don't think that's ever been a problem.  They are USB2 hard drives and I'm a modest home recorder nowadays.

I just went through this with my own C drive and downloaded WinDirStat (free utility) and it was VERY helpful in seeing what could be cleared off.

If you don't use hybernation, most people don't, and it's on, by default, turn it off. This will recover a substantial amount of hard drive space from the system partition, usually equal to the amount of ram you have installed on your system.

Also, old windows update files are another culprit as already mentioned I believe. Using disc clean up and selecting system files button should show the option for removing these.

Also, if you have any apple devices like iPhone, iPod touch or iPad, their files get backed up to the system partition by default and take a huge amount of space. If so there is a way to trick iTunes and move these files.

I've found these to be the biggest culprits to a disappearing system drive.

What kind of ports does your laptop have?  eSATA/USB 2/USB 3?
 
I would think an eSATA port would give you the best throughput, and eSATA external drive enclosures are pretty cheap (just load it with a regular 7200 rpm SATA III drive.   They might even make them for SSD drives, which would be a bit smaller.
 
Bob Bone
 

WDI
If you don't use hybernation, most people don't, and it's on, by default, turn it off. This will recover a substantial amount of hard drive space from the system partition, usually equal to the amount of ram you have installed on your system.

I just looked and the hibernation file C:\hiberfil.sys (hidden OS file) on my system is 12 Gb.
Definitely something to consider if you're tight on room.
 
Turning off hibernation in power management should get rid of it.
 
If you're going to be changing your system drive, consider a 120 Gb SSD with a 80 GB partition for the OS.  You won't regret it and you can use your HD for whatever won't fit on it.