I've test HD2000, the rasterizer (HD3000 engine) is loaded but the graphic engine panics as soon as you need to draw something real, test with 10.6.7 imac update perhaps 10.6.8 will have a driver.
hmm, I will be trying this over the next couple of days. I was going down the imac route as well but perhaps MBP2011 is better... May be need to match HD3000 GPU frequency as well. 10.6.8 is unlikely as there is no HD2000 in any mac as yet. will report back.