DDR doesn't necessarily work in pairs unless you are running dual channel which requires a matched set. DDR stands for Double Data Rate. I am testing my new rig right now with one stick(1gb) of my Dual Channel DDR kit. The Asus K8V-SE Deluxe is a socket 754 so it doesn't support Dual Channel mode but has three DIMM sockets. Here are a list of the ports on the board.
-2 x ATA133
-2 x SATA, RAID0, RAID1
Promise R20378 RAID controller
-1xUltraDMA133 supports two hard drives
-RAID0, RAID1, RAID 0+1