My current CPU is AMD Athlon X2 5000+, and it is a clear bottleneck in the more demanding games (BF3, ARMA II) as lowering video settings wont do a thing to increase FPS. I have been looking at the phenom X4 9XX CPUs, would they be good for gaming for the next few years? Intels CPUs seem a bit overkill and are too pricey, as my price range would be about 140€ tops for the CPU and ofcourse about a hundred more for the mobo.
Also, my GPU is Nvidia GTS 450, not the greatest but it gets the job done.
I can personally vouch for the Phenom II X4 955. It runs BF3 seamlessly at 1920x1080 and high settings, paired with a HD 6870 GPU. It would be well within your price range, so you could get a 965 instead. Or your could spend the extra money on a decent aftermarket CPU cooler, since the stock fan with this processor can be a bit noisy when it gets hot.
As for longevity, this processor should be good for at least a couple of years. And it's apparently not bad as far as overclocking goes, which is a good option to have in reserve
The disappointment with BD is that they suck against Debeb/Thuban (Phenom II) per core/mhz.
If you don't plan on overclocking go for the i3-2100 if you have a tight budget.
If you do plan on overclocking, a Phenom II X4 may be a stellar deal.
That was my plan for my 955 - use it stock for a while, then overclock it at some point in the future. But I've got a bit of spare cash now, so I'm probably just going to sell it and get an Ivy Bridge i5 next year.
On a budget the 955 is a really good processor, I would definitely recommend it