Great job, guys. Looks like you took my and others' recommendations to heart.
This has been the best $500 SBM build ever, from the CPU to the GPU to the motherboard.
The Phenom II X4 955 was overall the same speed as the Core i3-2100 stock, but overclocked it gained a good advantage. A 3.8GHz OC with a stock cooler is impressive, and the 2200MHz CPU-NB gave it a good boost in gaming and file compression.
At the target 1680x1050 and 1920x1080 gaming resolutions, much of the CPU limitations were eliminated and the Radeon HD 6870 shined through, especially when overclocked. All games were playable at both resolutions, though for titles like Metro 2033 you'd need to step down the settings a bit.
The motherboard is a much better choice than the one in the previous SBM, as it has a lot more features and expansion, not to mention a great price. The only negative thing I can say about it is that it won't support Bulldozer, while the other one would probably have support for Ivy Bridge.
The Power Supply is a great choice for only $45 and has much more headroom given the build, even though it had a lot less efficiency than the last, only consumed 317W at the wall for full system load.
I still find it impressive that you can get Memory for so cheap now. 4GB DDR3 is available for the price you could get 2GB earlier, and provides a good boost in multitasking and gaming. Overclocking the Memory doesn't provide a noticeable speed boost in anything other than synthetics, so I think it not going to DDR3-1600 speeds is not much to worry about.
The Hard Drive is standard fare and provides decent capacity, so not much to mention there. 500GB should be enough for a lot of games and media, and down the road an SSD could be bought to improve system responsiveness while having the Hard Drive for storage needs.
The Optical Drive is good, but I recommend for the next build you take a look at the Sony Optiarc as well. It has better read/write speeds as well as lower noise than the Samsung thanks mostly to its NEC chipset.
About the only thing I'd say was bad was the case, though I do understand that you're trying it out to see if it'd be better than the last one. The Xigmatek Asgard II is overall a better choice, and the HEC Blitz seems like a better choice than it though it costs $5 more. It comes with an intake and exhaust fan, and has many features.
Overall, I would have no qualms recommending a very similar system to a friend or family member looking for a cheap PC that can handle almost anything you can throw at it. Thanks for the great article.