An article on a Mac website (I think it's lowendmac.com) talked about speed comparisons between a 256MB and a 512MB iBook to see if the extra 256MB made a difference. The conclusion was that there was no difference when the app(s) are up and running but that starting an app was faster on the system with more memory. Tiger (that's the only OS X I'm familiar with) does a good job of making apps appear responsive across different CPU speeds. My kids use a 500MHz 578MB iBook and I have a 1.33MHz/1.5GB one and other than application launch times, the responsiveness (including web browsing) is almost the same. I cannot say that same thing about OS 8.x running on a 180MHz 3400c that we also have. So slooooow...... Ben