Hey guys, I just ordered a Mac Pro with 4x512 MB (2gig) from apple and would like to upgrade 1-2 more Gigabites over the next few weeks. I am wondering if I have to continue to buy 512MB modules, or if I can mix my existing 512MB modules with 1gig or even a single 2gig module. Does this work? Does it affect performance? I am also looking at third party ram, in particular from DealRam. http://dealnews.com/memory/prices/systems/Apple-Mac-Pro-/44047/1GB.html It says that it is Mac Pro certified and is pretty cheap. Any comments?