check out windows installer from support tools

Windows Installer Cleanup Utility Kills Apps

How *do* you get rid of an application that Windows won't let you uninstall? Use the Windows Installer Cleanup utility, which is included with Windows Server 2003 as part of the Windows Support Tools. This is actually a very useful article at SearchWinSystems:
http://www.wservernews.com/JDIGS8/060306-WinInstaller