If Syn's idea doesnt pan out? You might have to root through your regristry to delete the entries in the add/remove program files section. Its not terribly hard, but if done incorrectly could be hazardous to your system. You should ALWAYS make a backup of your registry before doing any work on it. And if worst comes to worse and you do not wish to root through your registry for the programs, you can simply remove the folders wherever they might be installed to reclaim the used drive space and just leave the programs in the Add/Remove list. No real biggie honestly.

If you need help with the registry stuff, I can root my other XP box and find the correct location where you need to look for them.