I have a early 2008 24" 2.8ghz i mac and i upgraded to Lion.. lots of freezing and beach balls. I have never upgraded my ram so i have 2gb. I was told that i could actually buy a 4gb stick and a 2 gb stick and i could get 6 out of this machine. Is this true? and if so where is the best place/ to buy 4gb sticks? I cant find them locally.. future shop hax Lexar brand but just in the 2 x 2gb packages, it seems worth it to upgrade to 6 if i can? thanks for the input.