hi!..i'm just wondering...what's the difference of having double RAMs and a single RAM...why would anyone have 2 1gb RAM than a single 2gb RAM...is there a difference in the computer's performance if you do this?

I don't think so choco. Sometimes people who have had 1 GB of RAM already might want t update and buy a new RAM so like that hey could end up having 2 RAM's in total which are 2 GB in total.