Oh well sorry if I cant help... maybe useing wonderfullIcon next time you install something would be a good idea ^^ that program keeps track of everything you install so it is easier to uninstall again.
hmmmmm.. most newer windows version have a function to go back to an older copy of your windows... say before you uninstalled the game if thats not to far back that is...
It should be quite simple after you found where it is. You just pick the date of the time your windows was to your liking and windows should completly remove everything you (or others) have done to your windows up till then.
You probely dont want to do that but it could be a way to fix it if you would do that..
other than that... you would have to remove everything in the registration database concerning vampire the masquerad and troika... can be quite a mess not recommanded for unexperienced folks since it can force you to format all and reinstall everything from scratch! (Which is actually the best solution anyway if you can reinstall and store everything you got)
btw, you dont need windows XP professinoal edition or any version of windows at all to get windows 64bit edition.... an 356 days evaluation copy is free from microsoft site, and what do you know when they updated to new version of the 64bit you got yourself another 356 days evaluation free
