That all depends on how much of a hurry you are in. AM2 is the future. Sure, it may not have the best scores at the moment, but in time, as the tweaking is done and developement gets going, it should get better. Since you already got the 4400, don't worry about the AM2, just use and enjoy what you got.
Conroe might also be good in the future. Don't know for sure. I've got machines with Intel chips and ones with AMD's. My experience has been that the AMD machines preformed better than expected, while the Intel ones were worse than expected. Except for heat issues on the Intels, they both ended up close to the same in performance. AMD has had a price advantage, but that seems to be changing.
Of course next year, or the year after, whenever Vista comes out, everything will change and we will have to start over.