The purchase is risky. Windows 7 comes with one license meaning it can be installed on one computer only. If the seller has already used the key, you will not be able to use it on your computer. The only way to get a guaranteed copy of genuine Windows is to purchase for a reputable retailer (ie Best Buy), a Microsoft Partner, or from the Microsoft store online.
Microsoft Windows Outreach
ok, what if it is not installed anymore, and no longer in any use? the guy said he formatted his harddrive before the teardown of his comp