I'm looking at the EVGA boards and they have their most expensive versions are the larger eATX and their less expensive versions are ATX/mATX. I spoke with a dell rep who said all their home comps use ATX, alienware uses mATX, and business work stations (with Quadro gpu) use eATX.
What advantages do each form factor have?
This is what i'm looking at so far:
Cooling ~$60/Case ~$140/PSU ~$160: eatx or atx x58, 80+ gold (750+ watt) (Corsair)
Chipset: ~$200-350 EVGA X58 Classified3 $350 (eatx), FTW3 $250 (atx), or SLI3 $200 (atx) or a (matx) chipset from a different company
CPU: ~$280 Intel i7-960
GPU: ~$260 2x EVGA GeForce GTX 550 Ti/560 Superclocked (sli setup)
HDD: ~$100 Hitachi 7k3000 6gb/s sata
Memory: ~$150 Corsair ddr3 4gb+ 1600mhz+
DVD-RW: ~$40
Sound Card: ~$40 Sound Blaster
OS: Windows 7 Pro
Total: $1,470 - 1,620
Ended up changing to sandy bridge 2600K (waiting for 2700) with EVGA z68 & ATX.