Looks like a pretty good deal, I personally would go for an SLI-compatible mobo so you can buy a second video card in the future if you decide you want some extra oomph. Also, Unless you've got a really nice power supply that's got some serious juice (over 500W IMO) I would want to consider getting a new power supply just to make sure you can keep up with that video card and CPU. You say add $100 if you need a power supply and case, but what about a hard drive? Optical Drives?
This is the setup I have been eyeing up:
ASUS P5N-D LGA 775 NVIDIA nForce 750i SLI ATX Intel Motherboard $149.99
BFG Tech BFGE88512GTOCE GeForce 8800 GT 512MB 256-bit GDDR3 $139.99 (after mail-in rebate)
Intel Core 2 Quad Q9300 Yorkfield 2.5GHz 6MB L2 Cache LGA 775 95W $274.99
Crucial Ballistix 2GB (2 x 1GB) 240-Pin DDR2 SDRAM DDR2 800 (PC2 6400) Dual Channel Kit $34.99 (after mail-in rebate)
LITE-ON Black 20X DVD+R 2MB Cache SATA DVD Burner with LightScribe $37.99
Seagate Barracuda 7200.10 500GB 7200 RPM 16MB Cache SATA 3.0Gb/s Hard Drive $79.99
Rosewill RP600V2-S-SL 600W SLI Ready-ATX12V V2.01 Power Supply $69.99
COOLER MASTER Elite 330 ATX Mid Tower Computer Case $44.99
Total: $735, not bad for a complete computer that can kick some butt. Also has good upgrade options in terms of plenty of HD spots in the case (mobo supports 4 SATA, but one taken by optical drive), can take more ram (up to 4gb), cool-running 45nm Intel CPU, and of course has space for an SLI video card set.
I didn't feel like a jump to DDR3 ram justified the price hike just yet, so I stayed with some pretty fast DDR2 that's nice and cheap. For the same price, I like the BFG Tech video card better than your eVGA one too. Actually the BFG is $10 cheaper since it has a $30 main-in rebate and yours has a $20 one, but anyway...