DOOM Denied

I tried to install DOOM3 twice, but it just wouldn't take. My win xp box has been acting flakey for a couple months now, and with the advent of XP SP2, it seemed like an auspicious time to nuke the dell and reinstall. A mere 6 hours later, we're just about done, and I'm now installing Doom3 again. This time, I hope it'll work...