4GB ram in your case is useless, in order to correctly adress all 4x1gb ram sticks you need to buy, you need a 64 bit OS, and your CPU is too old and has no 64 bit support. with 32 bits OS, like regular XP or vista, you wont be able to adress more than 3.00-3.5gb or ram, so 4 is a total waste...