As pooh noted, http://www.theeldergeek.com/ is an excellent resource for Windows XP.

For users wanting information on how the latest MS update may effect their system, check out:
http://www.winsupersite.com/FAQ/

More "tweaking" tips:
http://www.thetechguide.com/

http://www.techspot.com/guides-os.shtml
There are separate guides covering just about everything on your system (e.g. startup, internet explorer, system configuration, memory usage, etc.) which take you step by step and detail the authors reasoning behind each particular adjustment plus your options.

Need repair info?
http://www.webtree.ca/windowsxp/repa...Boot%20Sector:

For the Advanced User, wanting data on slipstreaming XP and burning CDs:
http://www.tacktech.com/display.cfm?ttid=295
http://www.tech-hints.com/

Hopefully someone may find these sites useful as well.

V.