Currently running XP Pro SP3 but it's becoming unstable after 4 years. Want to reinstall but not certain of the best method. I know to change boot sequence and boot from XP Install CD, but what pit falls might pop up and how to recognize and avoid them? [face=Arial][/face]

   You should not have to change the boot sequence.  It should already boot from the CD drive if there is a system CD in it.  So you should be able to insert the Windows CD and restart the computer.
   Reinstalling Windows to the same location will not do anything.  The installation program will detect that there is already a registry and will use it.  It replaces your files but the files do not go bad and it is possible that it will end up putting older files over previously updated ones.
   The only way to reinstall with a new Windows is to install Windows to a different directory (not C:\Windows) or to delete the Windows directory before installing (which is not easy and can be a real big headache and maybe even a disaster).  Both of these methods will require that you reinstall all of your programs.