If you still have the original Windows XP disc then before you go the whole hog and re-install why don't you try the 'repair' solution I gave the link to in post #4. Provided you follow the instructions it will not lose you any data or programs etc. This is a link to the full instructions:
http://www.informationweek.com/windo...no=1&queryText=
There are 5 pages - read them through and copy down the various steps as you won't have access to them once you start!! When complete you will have to go to windows update and re-download all the latest security fixes etc.