Alright, it's all ordered and should be shipped tonight
Ended up with, after some help from Calum:
Gigabyte EP43-UD3L Intel P43 Socket 775 Motherboard
Intel Core 2 Quad Q8200 2.33Ghz 4MB 1333FSB CPU
Corsair TX750W 750W Power Supply
Corsair 8192MB PC6400 DDR2 800MHz (4x2048MB)
BFG GeForce 9800 GT 512MB PCIe w/Dual Link DVI
Seagate 750GB Serial ATA HD 7200/32MB/SATA-3G
This should a nice diversion. should be a great folding machine, too... Heck, I could leave a Single Core client running all the time on real-time priority and just use my other three cores.
(I'll probably try the SMP client, though)