It depends on if you want to OC or not. If not, then get the 4000+, as it is essentially an FX, as I said. If you want to OC. then get a 90nm 3500+, as it should overclock past 2.4GHz, and past a 4000+ (if you're lucky), besides, its cheaper

.
IIRC, the 4200+ will be released alongside the FX-57, with SSOI (Strained Silicon On Insulator), along with SSE3. With SSOI, that should make for one good OCer, but only time will tell.