Windows 7 - W7 Best Option

I bought a used M2010 on ebay. It has dual boots from two drives, one Vista ultimate with key on laptop. The larger drive has oem Windows 7 ultimate. Everything was fine, activated well and was receiving updates. About a month ago the video card crashed/died and I had it re flowed..I get it back and it boots up with the date returned to 2007 and the Windows 7 drive has black screen with something about not being a valid copy. I reset the date, reboot and come back saying it needs activating..I entered the key(had it from Belarc copy) but it says it's not valid. I definitely like the Windows 7 better with the aero peek and larger task bar for my eyes. So what is my most inexpensive next step ? I am curious as to how this was loaded and continually working before the video problems? Since it's already loaded can I just buy a valid key?

Thanks. GBY

I believe you could buy a valid key and insert it as you would normally, but since it sounds like a pirated copy from eBay, I would probably want to wipe the drive clean and do a fresh install on my own, out of peace of mind.

Hi, Thanks for response. I don't think it's pirated as it says it's Dell OEM.

If it was previously activated, try activating by phone. Worth a try with nothing to lose.

Activate Windows 7 on this computer

If nothing else helps, give MS a call. They are usually very helpful: Activation and registration of a Microsoft product