First let me apologize for shotgunning questions about my new machine all over the forum. Now on to the next one. One of the upgrades on the list of must haves is a memory upgrade. My mac Pro is a 3.1 but the seller shipped it with 8 gigs of 667 ( four 2 gig sticks) So far my plan to save for four 4 gig sticks so if I ever actually need more, I have room for another upgrade. First, will I even notice the 133 Mhz difference between 667 and 800 mhz memory? Second, I have read that if all the memory slots are filled, the memory performs better. If I understand this correctly if your are going to install a 16 gig kit, filling all the slots with 2 gig sticks is better than filling half of them with 4 gig sticks. Do I understand this correctly? If so, how much REAL DIFFERENCE is there? Third, for final cut pro x, motion 5, and compressor 4 to function well, how much memory do I actually need?