Did you have DreamScene installed in Vista? If so, then this may be a upgrade issue from it. Either way, it's usually best to do a clean install to avoid any potential upgrade issue like this.
In your case you might consider a Custom Install
to have you current install dumped into a C:\Windows.old
folder in the new install so you can copy back any files that you may want to keep. You will still need to reinstall all of your drivers
and programs afterwards though.