with the macbook you'll want matching size pairs otherwise I'd recommend just picking up a 1GB stick to bring you to 1.25GB. But OSX is a memory hog so I'd get 2GB if you can afford it. At 1GB if I do more than surf the net and have Entourage open I start slowing down. Of course Netbeans and Weblogic are memory hogs too so that could be why things get slow.