I have a 3.1 MP, it runs my FCS 3 suite and I am a very happy bunny. I use it almost exclusively for FCS 3. With all the brouhaha over FCPX vs FCP, I see now reason right now to move up/sideways/down to X. I am actually thinking of staying with SL on the MP. But looking down the road, maybe I will need to sell MP, I'd like it to be fully upgradeable for the buyer. What's the chance that Apple will exclude my 3.1 MP from future OS's? I guess it will have to happen at some point, but what is it about the Xeon architecture that gives it long legs?