First off, OS X wants lots of memory... Running Parallels/Win on top of that means you are going to get very disappointing performance with only 512Mb (2 x 256Mb, right?). I'm running a 2Ghz C2D iMac with 1Gb and I get acceptable performance, but I will be biting the bullet and getting 2Gb very soon (2 x 1Gb..Arghhh!). A 1Gb stick, to give you 1.256Gb, is not expensive, and you should see good performance with it.
Last edited: Oct 13, 2006