(I have 2 sticks of extra RAM already - they say 'DDR512PC3200'. I can buy new RAM if necessary
and as you only have the two slots, to upgrade to 2Gb which you suggest you intend to do, in your post 41, you will have to buy 2 x 1Gb ram sticks.
My advice would be go here
you do not have to buy from there, and use the scanner
It will tell you what you can have, and indeed what you have