So my current machine, a MP 5,1 has served loyally and well as a testbed for all manner of programming projects. I'd like to expand its capabilities into GPU computing, and while the 5870 I've got in there right now can handle OpenCL based stuff, I'd really rather be dabbling with CUDA, which at this point seems to have better support. The problem being the Quadro 4000 costs as much as one of my kidneys, and I don't actually need that much horsepower. I'm looking for a "check that the code works" card before hurling it off to a server somewhere. Purchasing suggestions?