or you could buy 2x512 and run 3gb. to elaborate on crazeD's answer you need to run either 2 (2x1gb) or 4 (2x1gb/2x512kb, or 2x1gb/2x1gb) of your dimm slots to keep the memory in dual channel.
what do you do that uses that much memory, if i may ask?
two gb is enough for most everyday usage and gaming.
"nagasama no longer drinks tecate, or streaks out of the night for anything, and he has a fine wife so he has no use for your girlfriend...she is safe..."