2GB is great for now, but when windows vista comes out it's going to need alot of ram. And then when u play games on it u will need even more ram.
I'm going for 2x 1GB ddr400 soon, if I can get some cheap ones. Or then I'll just go with 4x 512 because I can get them real cheap.
If u can afford it get 2x 1GB dual channel now. Since if u buy one 1GB stick and then like 3 months later another one they probably won't work in dual channel.