DDRW
ram is good with 1 Stick of
ram. you can use 1x 512mb, or 2x 256.
you could even buy cheaper DDR2 4200 533MHz the slot will down grade the speed to match the rest.With DDR2 memory you can use fast memory in slower slot. But not slower memory in faster slot.
My board uses DDR 2 4200 memory, I have 1 GB DDR2 5200 in the slot and everything works to scratch. hope this helps