looks good, i'd go with the AMD 3800+ and use the extra $ to get a better graphix card, like a 7800GT or 7900GT (the ram, which you have plenty of, and GPU makes the biggest difference in gaming)
i dont think you get that much of a performance boost from the AM2 so i recommend the tried and true s939
maybe shell out the extra cash for a western digital Raptor (10,000rmp) HD
other than that you're probably money... build on