I usually go with two sticks of 256MB when buying RAM, because in the event one goes bad and is not under warranty, you still have another working chip and only have to buy another 256 stick to replace it, rather than a 512 going bad and needing to replace all 512 of your memory.
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"