Ensure the key is for a "Full Version" and not just an "Upgrade" key, which requires a previous version of Windows to be installed. How to Activate Once you have your key, activation is simple: Click the Start button and right-click Computer . Select Properties . Scroll to the bottom and click Change product key . Enter your 25-character key and follow the prompts.
Sometimes, companies selling refurbished hardware also sell excess OEM licenses. 3 Tips for a Safe Purchase buy windows 7 ultimate 32 bit product key
Sites like eBay often have listings, but be wary. Look for sellers with high ratings and a "Money Back Guarantee." Ensure the key is for a "Full Version"
As the most feature-rich version of Windows 7, the offers everything found in Professional, plus: the offers everything found in Professional