Hi, I have a 2009 Mac Pro (2.66GHz 8-Core) that shipped with 6GB (6X1GB). I'm looking install some more RAM. I believe my computer has 8 memory slots so I'd like to know what memory upgrade options I have. Can I add 2 X 2GB, or 1 x 4GB now, with the possibility of adding another 2GB or 4GB stick later. Are these valid combinations? I'm looking to upgrade to 10 - 12GB, and would like to do it in a way that my purchase is somewhat future proof so that if I need to go higher and replace some existing 1GB sticks, I can continue using my newly purchased RAM. I'd also appreciate any pointers to 3rd party RAM sites. Thanks!