For what it's worth, I just got the lowest priced i3 iMac (getting some motu stuff, needed a new mac to run it). Was going to get a mac pro, but decided I'd wait until I get PT HD to get that. It runs fine with Multiple instances of T-Racks, Ozone 4, Airverb, Alloy, VSTs, other plug ins and 32 tracks. Going to max out the ram in a couple of months, but it has no problems as a stock machine right now. Haven't tried virtual instruments on it yet though.