If you plan to add another GB later, I'd go with a 1GB stick now and add another 1GB. It's not a ton better but it is better to use 2 sticks instead of 4 (or 3)
That's if you can get GEIL to work??? I hear more complaints on that one brand of memory then PNY of all things. Corsair is one of the most stable as well as Crucial, Mushkin, Kingston, OCZ makes the premium list but GEIL? !