Boxing overshadows personal computers?
In what part thereof planet d do you live?
Why not just order on line?
What you need to think about is if the motherboard is compatible with the Video Graphics you want.
Solid State Drive? Have you done it before? RAID is still the better choice.
This life hacker article is a year old, but still is a good starting place.
http://lifehacker.com/5867465/most-popular-diy-projects-of-2011My point is that there are other things you can do as a hobby other that doing YAGM. (Yet Another Game Machine.)
Or,. just go to Newegg.com and they have recommended DIY projects for gamers.
Use what they recommend as a starting point.
Hope you have a good outcome.