You may want to wait to see what Penryn and Barcelona have to offer, because, if some of the rumors I have heard are true, they both may be major steps forward (maybe not core 2 vs P4 sized step, but still sigifigant). I assume this is a fresh build, in which case speedbird and nightscope give the correct advice. However, if you already have an AM2 MB, go with the 6000+ for sure. Otherwise, its a toss up.
If you are feeling generous, go with AMD and support the underdog.