I would suggest you buy a Phenom II x4 940 BE AM2+ though, no use buying a AM3 Phenom ifit's gonna be bottlenecked, and no use having some sort of backwards compatibility with AM3+ since u should be buying a bulldozer then.
and I would suggest a new single GPU to keep ur PSU light on load, maybe a HD6800
What do u think on the PII x4 955 to the 940 BE. Other then Price and clockspeed. I will be OC I see some good Benchmark on the 955. I also have a AM2+ board Asus m3a78-t will take any AM3 cpu with of course BIOS update which i have the latest and greatest. Also AM3+ haven't heard on the release. I want a good oc cpu. I have air cooled sys. next build will be water cooled.