[KarmaKiller]

Hi and welcome to TechIMO.
I'm just gonna make a build list. It's a lot easier for me, and I can promise you everything will work, and it'll be a great PC. For your $700 budget, I'd go with:

CPU:
E8400 is a good choice. If you wanna move up to a Quad, I would recommend the Q6600.

Motherboard:
You have a lot listed. Personally, I think your best choice is:
Newegg.com - GIGABYTE GA-EP45-UD3R LGA 775 Intel P45 ATX Intel Motherboard - Intel Motherboards

RAM:
4gigs is pretty much the standard now.
Newegg.com - G.SKILL 4GB (2 x 2GB) 240-Pin DDR2 SDRAM DDR2 1066 (PC2 8500) Dual Channel Kit Desktop Memory - Desktop Memory

PSU:
Newegg.com - Antec Basiq BP500U 500W ATX12V Version 2.01 Active PFC Power Supply - Power Supplies

DVD:
Newegg.com - SAMSUNG Black 22X DVD+R 8X DVD+RW 16X DVD+R DL 22X DVD-R 6X DVD-RW 12X DVD-RAM 16X DVD-ROM 48X CD-R 32X CD-RW 48X CD-ROM 2MB Cache SATA 22X DVD Burner - CD / DVD Burners

GPU:
I know you said you have the 8600gts, but I'm gonna save you some time and dissapointment.
Newegg.com - MSI N9800GT 512OC GeForce 9800 GT 512MB 256-bit GDDR3 PCI Express x16 HDCP Ready SLI Supported Video Card - Desktop Graphics / Video Cards
Get that card. It's worlds better then the 8600gts.

OS:
Newegg.com - Microsoft Windows Vista Home Premium SP1 64-bit English for System Builders 1pk DSP OEI DVD - Operating Systems
Vista is come to be a pretty decent OS. If your gaming, you want vista.

That would be a great budget build.