I was in a similar situation to you and I went with the 2.66Quad. Not worth the extra $500 right now, and I figure that is something to get later. As far as the imac vs mac pro. I guess it just depends on the money you want to spend. Coming from a pc world and this being my first mac, I just couldn't bring myself to buy a machine I couldn't open 😀 and I didn't' want a desk full of external drives. I got it with 8GB and ram and find that I use way more ram and much less cpu than I thought I would. I'm very happy with my machine. I also bought 2 24" dells which is the icing on the cake.