Well here is my own personal suggestion for parts.
CPU:
i5 3570
Motherboard:
Intel BOXDH77EB
RAM:
RAM is RAM
GPU:
MSI Radeon HD 7850
HDD:
1 TB
Case:
Bitfenix Outlaw
PSU:
430w Seasonic
Now for the reasoning behind my decisions. For the CPU I went with an Intel instead of an AMD because atm Intel is ahead on CPU perfomance. Also their motherboards are of a more modern design which is another plus. I did not go with a k model because I assumed you didn't want to do any OCing. Which is why I also didn't list a heatsink since the stock heatsink should be fine. Honestly this is probably more than you want, but I wanted to do an Intel list and I don't like recommending dual cores that much (the i3 is still a great CPU though).
Now onto the motherboard since you aren't doing any overclocking an H series board should be fine. As for why I picked the Intel board it's simply because I am a sucker for better LAN controllers. I went with micro atx simply because I dislike bigger boards you can pick a bigger one if you feel you need more expansion slots or you think you may want to do Crossfire/SLI in the future (not worth the money imo)
RAM is RAM really the main thing that matters for gaming is the Cas Latency/timings. The speed, by this I mean the MHz, has less impact really. Either way you probably won't notice the differance it's so small. If you want to know more about this take a look at
this article.
For the GPU I feel your 6670 will be the main bottleneck honestly. Now this may be more than you want to spend but I felt like it was a big enough perfomance jump over the $100-150 GPUs compared to what you have that it was a better value for your money. There is a 1GB version of this GPU but honestly I feel like that may hold you back in the future so why not spend the 20 extra bucks (note with the rebate that GPU costs just $5 more than the 1 GB). Oh and I just noticed it comes with a free copy of Bioshock: Infinite and Tomb Raider, which the 7750 or 7770 do not come with.
Well I just picked a 1 TB HDD just in case you needed one, but you could probably reuse your old HDD if you wanted.
The case is really good for the price really there isn't really much to say about it.
Here is a review of it if you want details of what it is like.
Finally the PSU, 430w should be enough, but if you don't feel comfortable you can always get one that is slightly bigger. As for the brand it's Seasonic which is a very good brand.
Now the total of all of this assuming you don't reuse the HDD, find any bundles, or use any rebates is $745.93. Now I did not include any rebates/bundles in here because they can be region/time specific so you can change around what I listed. If you want to save some money I would either go with an
i3 3220 (
Here is a comparison of the 1055T and i3. The i3 is much better in single threaded but the 1055T pulls ahead in most of the multi-threaded stuff. For gaming though most loads are single threaded and even multi-threaded games don't take full advantage of the multiple threads) or a
FX6300 (pretty much just plain better than the 1055T). You can find better deals I would assume for those 2 processors than the 1055T you were looking at, not to mention you could also find a deal on the i5.
Hopefully I covered everything, but if I missed something please ask.