I've got 4GB of ram and it seems like my usage is never going down. If I open up Firefox, MSN, iTunes, Limewire, etc, my iStat pro will show how much ram is being used and it obviously goes up to whatever is appropriate. My problem comes when I close all that stuff and it doesn't show the usage going down at all. When I click on it to see whats using it, it shows a kernal task. Now if I restart my MB the usage will return to barely nothing. What should I do?