I currently have two dual-channel DDR2 memory sticks totaling 2GB set-up. I want to upgrade to 4GB. Should I buy the same model again or it does not matter? Thanks for the help in advance.
Assuming you have two free slots, you do not need to get the same kit again. You should make sure that the new memory has the same (or higher) DDR rating (DDR2-800, DDR2-1066, etc). You also should (bud don't have to) check that all the timings are the same or lower (for example, if the old memory is 9-9-9-20, then the new memory should have all the same numbers, or lower numbers). The most important thing is the voltage...make sure that the new memory kit uses the same voltage as the old kit.