Pantsie, have you tried the "fail save" option? I dunno if it's called exactly like that, I'm running the bloody thing in Germon after all, but if you press F8 when your rig's booting up Windows, you get to a menu that gives you options.
edit: what jacog said!
Then there's also the possibilty to re-install the OS or just try to fix the current installation, which actually doesn't take THAT long.