For gaming its more about the GPU than the CPU dont get me wrong you still need a good CPU but an AMD Phenom II x4 will be plenty of power for gaming. If you need a CPU for raw power get an I7. But I would also wait for some concrete benchmarks for the Phenom II x6 line.
But yes AMD price to performance you cant beat it.
Well, up to the 955BE. They pretty much own the $50-$100 segment and make sense up to the 955 which is around $160 I believe. Intel's i3, for $130, competes alot better than I thought it would, especially if you overclock it. The X3 and X4's around that price are still good though. For a little more you start looking at an i5 750 (which is an excellent overclocker). If your total budget is $1000 or less, then AMD is a good choice depending on what you want to do. For $1000-1300 it just kind of depends, and above $1300 I pretty much say an i7 920/930 build all the way
Well, it couldn't be said so simple that intel i7 or phenom 11 is better.. There are cases in which intel leads, but there are cases in which amd. As megamanx00 said, it's just kind of depends.. It's your choce (price category, what do you want to do with the system, etc. etc.)
what L3Wy said... it depends on what you want to do with you rig... I'd recommend a Phenom, with an ati gpu if you're looking for gaming because ati is the best bang for your buck, and i've read some reports about ati and intel cpu's not co-existing well...