400-450$ Budget - How well would this system run?

The Phenom is pretty weak and outdated right now. The 7770 is a pretty decent card. Together,you'd be able to play less demanding games like Minecraft,MMOs etc at high-ultra settings and next-gen games like BF4 at medium-high settings.( BF4 hasn't been released so this is just speculation)

If you don't intend to max out games then this would be a good build.

the phenom ii x4 965 isnt really a good choice anymore, maybe if you overclock it but then it will draw more power and not last as long and you will need good cooler for that anyways, even on a better processor, its always better to use a cooler and quieter operating fan, now for gpu, the amd 7770 aint bad for that price however the a10 6800k just got released and your better off sacrificing a little gpu performance for better cpu performance and less price since you wont need a dedicated gpu to play all those games you listed, you can play them on low-medium on good frame rates. 8gb of ram is good, all your other specs are good except obviously changing the motherboard to a fm2 one for the a10 6800k, now i wouldn't get the a10 6800k yet, i would wait to see if the price drops down in like a few weeks or something, it seems a little pricey right now for about 150 dollars, also for the motherboard, dont get a really expensive one, just get one with basic features, if at the time has good reviews, preferrably around 50-100 dollars.

you can play all games at 1080p at medium also AMD phenom ii x4 is a great cpu still its a quad core and it can run all games still so don't listen to anybody that says it's outdated cause games nowadays still recommend duel cores some games like Metro, Crysis, and Witcher are mostly the only games that recommend quad cores so I hope you enjoy your build it's a great one for the money

game one

~ShadowOfNexxus

It should handle most games reasonably well, but BF4 will likely crush it, and more demanding games like Crysis 3 or ever Far Cry 3, will be a struggle.

It would run ok medium settings at least .

very well config iam also using this config only

It should be fine.