Definitely, the nVidia GPU2 client offers the best bang for the buck for producing output for our team. And they're fairly easy to set up using the system tray version.
I also got my C2D running again, and for the moment it's running at 3120 MHz which is better than it was before. I wouldn't be surprised if my Crucial Ballistix DDR2 chokes on me at some point like the first pair did, though.
I've checked eBay the last few days, and people seem to be selling 8800 GT cards at pretty reasonable prices. Today an 8800GT-256 like mine went for $71 shipping included
, which is cheaper than I got mine for if my rebate comes through. Here's another
that will be done tomorrow morning, currently going for $78, and at 512MB a better card than mine.
I would advise anyone with a system with a free PCIe slot to try to buy one and get it going. As I mentioned elsewhere, before I overclocked my 8800 it was using about 46 watts, and the entire system, an A64-3200 at stock CPU speed was using ~166 watts. Fairly inexpensive considering the great output.