I'm going to upgrade my system in the spring. I know that's a long way off yet, but I got to thinking about it. Which is better? 512 MB PC2700 or 768 MB PC2100? I'd rather just add 128 MB of PC2100 to cut costs a little bit. But if 512 MB of PC2700 will give noticably better performance (primarily for gaming) then I'll go ahead and get it.