If it downloaded the genuine advantage tool that keeps telling you that you may be a victim of software counterfiting there's a really easy way to take care of it. There are two files in the Windows\System32 directory that cause your headache. One is, IIRC, legitcheck.dll and the other is something like WGA.exe or WGAtool.exe, anyway, it stands for Windows Genuine Advantage. You cannot delete the EXE because it's in use and when you kill it through Task Manager it restarts immediately. But all you have to do is rename the legitcheck.dll file and restart the computer. It tool won't start and you can then delete both files.
Rather than deal with circumventing MS's anti-piracy measures, which will, over time cause you quite a bit of headache, I'd just give them a call. If you actually have a legit copy they'll activate it over the phone. It'll take a few mintutes, but then you don't have to worry about it ever again. Beats having your system periodically screwed up every six months whenever MS hatches some new anti-piracy measure.