Just some quick tips to clear off some disk space:
Clear out C:\Windows\Temp
(Find the folder, press [ctrl]-a inside the folder, then [shift]-[del], any files/folders it says are locked, unselect them with a [ctrl]-click and press [shift]-[del] again.
Clear out user temp folders
XP: C:\Documents and Settings\
Windows 7/8: C:\Users\
(Find the folder, press [ctrl]-a inside the folder, then [shift]-[del], any files/folders it says are locked, unselect them with a [ctrl]-click and press [shift]-[del] again.
Open Up Browser of choice, and clear internet Caches
Internet Explorer
Tools > Internet Options
General Tab > Browsing History > Delete….
Firefox
Tools > Options
Network Tab > Cached Web Content > Clear Now
Check for memory.dmp in C:\Windows\System32 or C:\Windows
Safe to delete it
Check for minidumps in c:\Windows\Minidumps
Safe to delete them.
Finally, Right Click Recycle Bin and click Empty Recycle Bin
If the Computer is XP….(Don’t do this on Vista or Windows 7/8)
Delete hotfix unisnstall folders
Look into C:\Windows, delete any folder of the form $NTUninstallKBXXXXXX$
Delete any folder under c:\windows\$hf_mig$
**DO ANY OF THIS AT YOUR OWN RISK **