ahh! Hmm..well then you MUST have gotten a recovery cd...but if you cant find it...
I think that it would be legal to use someone else's disk or even download one, SO LONG AS YOU USE ONLY YOUR CD KEY ON THE COMPUTER
I'm not 100% on that, but it sounds pretty fair to me! If im wrong and it's illegal then don't do it. But id not..hey, problem solved...
Good Luck.
