It'd be easy to get 2gb of RAM on that system. You'd simply insert 2x 1gb PC2700 chips, though I wouldn't think at all, that this would be worth doing, as 1gb is plenty for any system at the moment (might become the standard soon though as 512mb is at the moment)
Plus I'm afraid your motherboard doesn't support Dual Channel, so wouldn't support Dual Channel RAM in Dual Channel mode, so apsoloutley no point getting that.
DDR I think only supports Dual Channl anyway, and your system only supports the older SD-RAM which came before DDR.
So just get 1x 512mb Samsung RAM then (same as your system) which is un-dualed, since the chip inside your system at the moment won't be (get the same chip)
I hope this helps