Mail question... how do i save a copy of all incoming/outgoing email to harddrive?

[vwcruisn]

I just signed up for .mac today. Im loving it. I previously had AOL and i think this will make my life easier. My question has to do with the email. With aol.. i would get email... and i could read it.. delete it.. whatever.. but a copy would be saved to my computer so i could view it down the road if i needed to. Can I do this with Mail? I like keeping my inbox empty except for unread mail... as soon as i read it.. i want it out.. so leaving it there isnt an option for me... also.. is there a way to save sent mail to the hard drive?