Re: amd athlonII x4
If you want a CPU for gaming.
A Phenom II X2 outperforms all Athlons for most games. Athlon II X2, X3, X4
The only games the Phenom II X2 might lose to the Athlon II X3 or X4 in is stuff like GTA IV that are CPU heavy.
Even so, you usually have good odds of unlocking a Phenom II X2 to a Phenom II X4, and with the right motherboard you're almost guaranteed at least a Phenom II X3.
If your objective is gaming, I'd go with a Phenom II.
If your objective is to just have an all around good computer on a budget...
Then again, the FPS difference between an Athlon II X2 240 and Phenom II X4 955 with the same graphics card would only be like 10 FPS max.
And saving $100 by going with the Athlon would enable you to buy a better graphics card, thus defeating the Phenom II X4 955 in gaming.
It's really just a matter of what fits your budget + what you want to do with your computer.