Dual core CPU's suck at gaming, So unless you want to render in 3ds, rip mp3's, play mp3's, have 34 internet exploer windows open, and compress files at the same time dual core is not worth it.
For the top of the line Dual core you can get a FX-57 which is alot better for gaming.
Rule is, don't buy dual core unless you are goign to multitask alot.