Quite Major, the difference between the 2.4 and 2.8 is even more, since the 2.8ghz is a core 2 extreme dual core (mobile, as the 2 duos). I would recommend 2.4 to anybody, or a 2.8 for people who do some professional things. the 2ghz, correct me if im wrong, IMO, Has to be out of desktops. Thats a laptop thing now, I don't think desktops should be equipped with that, its getting really outdated, but max it out with 4gb, you should be OKAY, but i still recommend 2.5 any time.