I currently have the 2.0ghz Core Duo MacBook Pro. The machine is nice and does what I need it to do, but sometimes I feel it hangs or lags. I've got the memory maxed out at 2gb and wish I could stick more in. Coming from this machine that is now getting up there in age, would I notice a large speed increase, or would this be a waste of money? Also, I like the idea of a 13 inch screen, would a MacBook be faster than my current machine? Though there are features I really love about the MacBook Pro that the MacBook clearly lacks. Thanks in advance!