The Windows Update SoftwareDistribution directory (C:\WINDOWS\SoftwareDistribution\) can easily eat up a few hundred megabytes of space due to all the downloaded updates (in the download dir).
Windows does not delete these, and it would be cool if ccleaner would be able to clean this. Especially since we are talking about so much space here....
I've used both the automatic Windows update and manual updates for over a year. I've never intentionally cleaned out my C:\WINDOWS\SoftwareDistribution\Downloads. Total accumulation = 2 files for 50 KB in total.
My understanding was that not clearing itself generally means something went wrong with an update.
:-| I've seen installations with several hundred MB in them. Do you use Windows Update from the web?
I run XP Home with SP2. Patches are via automatic Windows Update. Now I checked again Downloads subfolder. It has only 3 items - total 65 kb. So OS has cleaned it automatically from 5,75 Mb to 65 kb.