I have on: Riser 1: 2-512MB sticks of Nanya RAM Riser 2: 2-512MB sticks of Crucial RAM For a total of 2 GB RAM I want to add Omni-Technolgies RAM on: Riser 2: 2-2GB sticks For a total of 6 GB RAM I can get it for $185, including shipping as advertised, and it seems to be a great deal. Is this a good idea or a bad one to mix and match? My past experience tells me this is a bad idea, but if it passes parity tests, then it should be fine. I'm going to upgrade to Leopard next week and then order this RAM. If I order 4 GB (4-1GB sticks) of Crucial RAM from Newegg, it wil cost me about $338 which is about $138 above my $200 budget for RAM upgrade. I got the Mac Pro in Sep 06, and plan to keep it until 2011.