actually, the DFI board has 2 regular PCI slots and 6 USB 2.0 ports
I would suggest the Athlon 64 3200+ or 3000+ Venice - they are both the same core but at different clock speed. they both overclock to the same maximum speed. take that into consideration if you are overclocking
the Nvidia 6600 GT is a very good card for the money. $170 and it can play Doom 3 at high settings
otherwise the 6800 GT is even better (although more expensive, about $350) and very future proof
do NOT get a low quality PSU. PSU's are very important. if it is not very good, it can take out the entire system
OCZ, Antec, Thermaltake, Enermax and Cooler Master make good PSU's. you'll want at least 450W and look for the rails (+12v, +5v and +3.3v). it should have at least 20 Amps on the +12v, and at least about 15-20 on the +5v for good power flow.
also, for RAM, G.Skill is the best for overclocking. if you can afford it, get 2x512MB of it.
otherwise OCZ makes very good RAM. don't get Corsair.