With relatively low RAM prices, 2gb is definitely worth getting these days.
Dunno whether in future got bh-5/ch-5 coming out with 1gb sticks?

Currently on 4 X 512mb @2T @ 2.5-3-3.
Feel much happier on this setup compared with 2 X 512 @ 1T @ 2-2-2.
Even though running pathetically @2T and lower timings, games and certain applications are performing better now.