Hi. I just purchased a new motherboard and CPU and was looking for recommendations for RAM. I have a MSI K8N Diamond Plus with an AMD Athlon X2 3800+ CPU. I'd like to purchase two 1 GB modules, but am unsure which spec that the motherboard supports to use. At some point I would like to double up to utilize all 4 slots. Any recommendations out there?

Look in your user's manual, starting on page 23. It gives you all the information you seek. I am in the process of building my computer using the MSI K8N Diamond Plus and it appears that the XMS series for Corsair (2 x 1 GB) is probably the most likely way to go.