I recently installed Leopard on my somewhat older MBP. It on about 18 months old now and running like a champ. It really has been an incredible machine especially with the work I do. I do high end audio/visual production and I am constantly on the road from show to show. So you can imagine the amount of minor abuse it has to go through from city to city in my bag bouncing around. So anyway, Leopard has been running pretty good, besides a bunch of permissions that won't repair though this seems to be no big deal, but I am wondering how much gain do you guys think there is to see performance wise with the older generation? I believe I am not 64 bit, correct me if I am wrong, and do you think I am not seeing what a lot of other are being core duo and not core 2 duo santa rosa? Personally I do not see much gain and if anything I think it takes a bit longer to boot up. Any others on the core duo's notice any gain in speed?