You have a
soket S1 motherboard so you have to get a socket s1 processor. Unfortunately I didn't not see that as an option under new egg for that so it might have been discontinued which leaves ebay or some other online auction site.
Unless you are continuously near or over your 2 gb physical capacity the only benefit to getting more ram would be if you computer supports dual channel & I'm not seeing if it does. Something for you to research.

I'm sorry that I can't give you any thing else now but I don't have time to look now.