I bought (perhaps too hurriedly) a motherboard:
Newegg.com - ASRock A770DE+ AM3/AM2+/AM2 AMD 770 ATX AMD Motherboard
and some NICs:
Intel PRO/1000 MT Dual Port Server Adapter - Overview
The nics supposedly will work with 32 or 64 bit PCI slots, but looking at the shape of the PCI slots on the motherboard and the shape of the video cards, I'm worried they won't fit

Will they?
And as a minor gripe, it's hard to find motherboards with enough slots. I needed about 6 PCI slots and it seems like 3 is the best I could do. (It had to be a socket AM2 board)
One more minor side question: do 64 bit PCI cards fit PCI express 4x slots? Don't think they do, but doesn't hurt to ask