xRegent :
One more kind of on topic question, how many times can I use the same Product key on a single computer?
If you own the retail version of Windows, you can reinstall it as many times as you like, whether it is the same computer, or a different computer completely, as long as it is only installed on 1 computer at a time. That is the advantage of the retail version.
If it is the OEM version, it costs half as much, but you can only ever install it on 1 PC. You can reinstall it on the same PC again, but you may have to contact Microsoft for a new activation code. You cannot ever install it on another system.