I usually delete my Windows XP Hotfix folders and .log files, by year:
Example path/filename: C:\WINNT\$NTUninstall######$
I just finished sorting the WINNT files by date, recording the filenames of the 2005 files (folders and .log files), and copying them to a CD-R before deleting them from my hard drive. I kept the 2006 folders/files.
Then, of course, I had to go into Control Panel, Add/Remove programs, select "Show updates", and click 'Remove' on each of the ones I deleted, in order for Windows to offer to remove them from the list.
This can help free-up a lot of space if you haven't deleted these old files for years.
