Building/Buying a gaming PC

Thanks for the recommendations guys, I'm goin' to bed, but I'll check 'em out in the morning.

I just wanted to say, forget about the extra money I had, I forgot to get an OS.

http://www.newegg.ca/Product/Product.asp...-_-Product

I'm confused about the whole "for system builders" thing, but I'm assuming it doesn't really matter. Could someone clear this up?

It's OEM. 1 time use, tied to the motherboard. If you wanted to switch or upgrade your MB, you would have to call microsoft and see if they're nice enough to let you reuse.