I have 2x512mb of ddr2 667(5300) ram right now. I am wanting to upgrade to 2gigs of ram, but I want to know which would be better? I could buy 2 more 512s to make 2gigs or I could wait about a month or two and buy 2x1gb sticks. I really really don't want to have to wait to get 2x1gb sticks. So, is there a big performance difference between 4x512 and 2x1gb ram. I heard that you can run dual channel with 4x512. If that's true then I will probably get another 2x512. So can anyone tell me the pros and cons of the two?