I notice a lot of build videos don't put in the cost of the OS and I found a cheap alternative to Windows 7/8, Windows Home Server 2011. It's only $50 and I don't care that it's a Server OS, just as long as the drivers work and you can play DirectX 11 Games, it doesn't matter. However, I think it would be wise to get recovery software because it's an OEM Disc.
the price of windows home premium is going to go down in the next month or 2, its already gone down 60 dollars