You can use any brand, unless you're buying a 256MB chip. If you're looking for 256MB RAM then make sure is not high density. The chip needs to compatible with BX chipsets.
BUT, a big butt, if you're making this question it means you're not very familiar with this board. And this board can be a real challenge. So be prepared for a possible wild ride while you perfect your system.
The board is worth it, but it can take away many hours of your sleep.
Good luck.