Windows 8, why? Its crapola. Stick with 7 for the love of God.
Have you even used Win8?
I have it on my gaming pc and just put it on my laptop. It is so much faster with better overall performance when compared to 7. Boot times were cut in half when I switched to 8. Also, Win7 isn't being supported anymore and Win8 will just get better down the road (especially whenever Microsoft "Blue" gets released). There are also many ways to get a start button back. I used Start8 and after that's installed, you have everything that Win7 has and then some (Metro/Live tiles if you want to use them, but you don't have to). I've also never had any driver issues for any of the hardware in my gaming computer nor my laptop.
There really isn't any reason to continue to use 7 unless you are being forced to (work/school) or you don't have the money to buy an upgrade.
Also, OP, there are ways to use the upgrade key for a clean install, but unfortunately I can't give you any links because that might be considered piracy on this forum. I actually just read something a couple days about doing it with a couple commands in the command prompt.