Is it worth upgrading from my Athlon II X4 645?

I was thinking about upgrading to a Phenom II X4 black edition. Whichever one is best for gaming. I have an Nvidia Geforce 460 GTX XLR8. The graphics card comes factory overclocked and gives slightly better performance than the 465 GTX. Got it for only $95. I have 8GB of DDR3 1333MHz RAM. I would rather have intel but I already had the AMD CPU and motherboard and I don't have a real whole lot of cash. My motherboard is an ASUS M4N68T-M V2. It doesn't have very good overclocking options so unfortunately I can't overclock my Athlon II far enough to see any real performance gains. I don't like going over 210MHz FSB because it won't let me lower my HT link multiplier and it becomes unstable. It does fairly decent in most games as it is but I was wondering if it might be worth upgrading. The Athlon II X4 seems kind of underpowered.

In gaming terms yes, you would gain anywhere from 14%-31% from the benchmarks. I upped my Nephews Athlon 630 up to a Phenom X4 955 O.C to 3.9 GHZ, and felt it was well worth it.