Cleaning Windows XP
A very few not obvious hints to clean Windows XP and get some free space:
If you manually delete some files or the entire folder you couldn't be able to uninstall the related software via Control Panel.
Since some of them could be orphaned installers, you can find and remove them using MsiZap, a Microsoft utility released with the Windows SDK, but if you want to just download MsiZap go on nerdoftherings.net, then run
msizap.exe !GThis utility will find and remove orphaned uninstallers, thus free some space (according to somebody it could free tenths of GB, in my case just a bunch of MB).
This is the history of your system: see here; thus it can be deleted