With that (or any NForce2) board 2x 256 is defenitly better. It supports dual channel DDR. Which requires the use of 2 chips.
As for that motherboard (I have one) the only problem I've ran into is the on-board NIC won't work on 10MB mode. Might just be a driver issue, but I can't get mine to work with a 10 MB hub, works fine when I'm plugged into my 100MB switch. Other than that I have had no problems with the board.
"Quotes are for people that can't think for themselves"