Ok - took the plunge. Here's what I ordered from Tiger Direct for ~$1400:
3 x 6950 2GB
1GB DDR3
890FXA-GD70 mobo
Sparkle 1250w Modular Power Supply 80+ Gold
AMD Sempron 145 2.8Ghz
***Cooler Master HAF X ATX Full Tower Black
The case was probably overkill, but DAMN! it has a lot of fans on it!! I couldn't resist - and heard great reviews. Plus, I had to cram everything into something, right?
Anyway, I'm hoping for 1GH/s (at LEAST). I have a crap load of HDs laying around, but I have even more thumb drives. What's the preference?
Also - what software should I use (I'm leaning 99% UNIX). One I start mining these suckers, I can 'reward' folks who help me out. I'm really new at this, and it would be worth it to me.
OBTW - with those extender cables (or whatever) I was reading about, how many GPUs can I fit in this case/mobo combo. I have PSU and cooling to spare, but not sure about the space available. After the initial rig is paid for, I'll be adding GPU(s).