My white plastic Macbook (1GB RAM, 2GHz Intel Core 2 Duo), I got in April 07', has been running very slowly lately! I don't know why. Simple apps such as Safari give me the spinning wheel. Don't even think about running Skype and Safari. I really don't know why! In May I got an iMac and that day it did not seem as slow. I really can tell it is not what it used to be. Any tips?