Heyyo,
Well dude, your cpu's just fine man. Of course you'd get an increase in framerates for games if you bought a FX-57.. but I bet you'd see a bigger increase in framerates with a new vidcard, and at a lower price too. Like mentioned before in other, you could try getting an evga 6600GT or another good brand. Even better, see if your mobo.. oh wait it's dell, nevermind, you'll probably need to buy a new mobo that supports SLI, and then buy 2 6600gt's (have to be the exact same cards!) and throw them on your new mobo that supports SLI and run those buggers as 1 and there ya go, incredible framerates. That's like, half the price if not less than the FX-57 but your ability to play games on higher settings will skyrocket. 2 6600GT's in SLI is probably the 3rd best setup you can do for vidcards to date. So that's damn impressive stuff man.
So yeah, new cpu's do help, but remember, when it comes to gaming priority #1 is the vidcard.
well, if you wanna do some hardcore computer calculations n' whatnot or encoding.. then sure, they say the fx-57 will be the last, and best single core cpu made.