Vertex 2 is one of the best SATA 2 ones (unless you work with lots of incompressible data like images or video files on that drive), but if you plan on moving the drive from this to another PC in the future, SATA 3 would be more future-proof.
Looks like this board will only support 2GB max per memory stick, so you'll need 4x2GB ones. DDR2-800 ones like you've already got should be fine. I looked at the memory compatibility list and it doesn't list any 2GB sticks, so make sure you can exchange them if they don't work.
http://www.memoryexpress.com/Product...19356(ME).aspx