Depends. Windows does not need anything listed here, but your hardware
and some applications may. See "How to Troubleshoot By Using the
Msconfig Utility in Windows XP"
(http://support.microsoft.com/?kbid=310560).
You can have too many programmes running in the background. Close
programmes/windows after
use. Check whether all the programmes loading when Windows is started are
really necessary. http://aumha.org/a/loads.htm