SS = Single Sided (Memory chips on one side of the DIMM)
DD = Double Sided (Memory chips on both sides of the DIMM)
CL is the latency of the memory. Lower latency is associated with faster performance. Typical PC3200 DDR memory has 3, 2.5, or 2 cas latency with 2 being considered the best. CL is also refered to as CAS by some manufacturers.
I don't know what kind of budget you are working with, but I would reccomend you look for a dual channel kit (2x 512mb) from a quality manufacture such as Kingston, OCZ, Corsair, or Crucial. If you can afford high performance CAS (CL) 2 memory, I say go for it. I use Crucial Ballistix with no overclocking and think you should consider this memory for your setup.
As far as the qvl ram goes, as long as you go with a good company like i listed above for PC3200 ram you should not have any compatiblity problems.