AMD regains the value option with 4100 FX and for those with a very limited budget it makes a reasoned and rational choice.
Firstly, it is cheaper then the alternative 2120, but offers an extra 3%-5% on average for performance.
Secondly, you're not paying for wasted GPU silicon on the CPU when you've got a proper graphics cards for gaming!
Thirdly, unlike the 2120 this CPU can be overclocked up to 4.6 GHz (4 GHz without voltage increases). An easy gain of 27% in performance, which puts it ahead of 980B, which costs an extra 60% over the 4100 price!
Fourthly, Windows 8 2012 release will see an extra 2%-10% gain in performance through more even threading between cores of workloads. This CPU family architecture is specifically designed for servers which have software with even spreads of workloads for the available cores. Desktop PC's tend to have a lot of software that pile workloads unevenly onto cores. Microsoft and AMD are working together to ensure the new OS has more equal loadings, which is where this extra performance will come from.
Mine's is running 4.2 GHz with no problems. No problems with video games with my Asus motherboard. However, I don't use Steam (I do have an account) and GameStop (formally Stardock Impulse) has not shown any of these problems.
A good value choice during these hard times!