I have a 2.66ghz Mac Pro and have been running it with 2 gig (4x512) memory. I do a lot of multitasking and get a fair amount, though not what I thought was an excessive amount, of page outs. I picked up a pair of 1 gig Crucial memory modules and installed them this past Friday, bringing me up to 4 gig of memory. I cannot believe how much more snappier my system feels now - and this with the memory not running in quad channel mode . I bumped up the memory for my XP virtual machine to a gig which helped it out a ton and the rest of the system is now flying along. I should have done this a long time ago. It is tempting to add another 2 gig and go back to quad channel mode, but that is a luxury I probably really don't need at this point. I'll wait and see how the new Photoshop sucks my memory before making that decision.