If I was building a gaming machine I'd get an 8 core AMD chip and a motherboard with at least 2 slots that fit the video card you picked (so you can add a second one and SLI it later if you need it)

since the faq specifically recommends using an SSD I'd get 3 250GB drives and use the built in windows soft RAID to make them all one volume, so you'd end up with a single 750GB C: drive. You're losing out on redundancy, but who cares on a gaming rig.