Either actually works. I have the same PC as an HTPC in my house. The issue - only 3.2GB RAM will be recognized due to a limitation on the motherboard.
Make sure you get a matched pair (1 kit containing 4 X 1GB sticks) - if not, you will have issues. I mixed RAM, and it had random blue screens until I replaced the RAM with one kit.
so there IS 4 slots huh
also wheres the cheapest spot? I found 2 2GB dimms for like 50 bucks that seems cheap