"Downgrading" to Windows 7

Dime_Eater

Honorable
Aug 20, 2013
15
0
10,510
I built a computer about 7 months ago and at first I had Ubuntu installed on it. Then because of compatibility issues, I decided to "upgrade" to Windows 8. After a few months of Windows 8, I couldn't stand it. So I'm wondering if I can "downgrade" to Windows 7. I have Windows 8 Pro, and its product key.
 

Dime_Eater

Honorable
Aug 20, 2013
15
0
10,510
I was searching the web and saw that you could use the product key that came with your Windows 8 disk. I have an installation disk for Windows 7, but it doesn't come with a product key because I brought it from work.