Toshiba problems with iTunes upgrade

I have a Toshiba Satellite laptop and a 5th generation iPod. I have used iTunes succesfully for about 9 months, but then I tried to upgrade and now I can't open iTunes. I think the error might be with Toshiba and Quicktime. The error I am getting says that the new version of QT can't install because the old version can't be uninstalled. I tried to uninstall QT through the Control Panel but it doesn't work. I also tried deleting all files that deal with QT and iTunes, then reinstalling. When I install, iTunes installs completely and then QT never finishes. I then try opening iTunes and it says that files are missing. This is the same problem a friend of mine had with the exact same computer. I'm frustrated because I don't have anyway to update my new iPod, please help me.

Toshiba Satellite Windows XP P4