If this were me, I'd do a search for any files/folders that were related to the game, and delete them. I'd then do a defrag, and run CCLEANER
to help clean out the registry (those files that might be left behind by the game). I'd reboot and then try reinstalling the game.
If you have problems installing the game, do the above again, but before you install it, run adaware or whatever malware prevention/cleaning programs you have, then run a virus scan, unplug from the internet (unplug your ethernet cable, or if you're on dial up, don't dial into the net) and disable any firewall that you might have running, as both the AV and FW might prevent a complete installation.
I know that some people say that deleting a program file is bad, and I can't argue that point, however, I've been in the same situation as you and I've done what I said above and had good success with it.
Hope it helps!
War produces veterans, wounded both physically and mentally. They have sacrificed for us.....and it is now our job to help these veterans, as they have already helped us in ways we will never know, in ways that we cannot fathom, and in ways that we take granted every day.