How is the startup time after you made all those changes in Autoruns?
You should also get more RAM. 1GB would be ideal for XP.
Go Start>Run ("Start Search" in Vista), type in:
Click OK (hold CTRL, and SHIFT, hit Enter in Vista).
Have Windows CD/DVD handy (with Vista, most likely, you won't need it).
If System File Checker (sfc) will find any errors, it may ask you for the CD/DVD (rarely in Vista case).
If sfc won't find any errors in Windows XP, it'll simply quit, without any message.