Phenom II 720 x3 AM3 vs 940 x4 AM2+ for gaming

I have two concerns here:

1) Gaming performance
2) Future-proof

1) I will be running 4870x2 @ 1920x1200 res. on a 24'' monitor. Will there be a noticible difference in game performance with these two cards?

2) The 720 is only triple core but AM3 socket. 940 is quad core but only AM2+ socket. Since the mobo I'll be getting supports both AM2+ and AM3, I could theoretically upgrade the CPU in the future to another AM3 socket CPU. The 720 allows for DDR3 memory, while the 940 only allows for DDR2. (I think all that was right).

Thanks for you're help!

If you have an AM2+/AM3 mobo, I am sure it only supports DDR2. AM3 socket mobos are not backwards compatible with AM2+ CPUs.

Mmmm it really depends, in technology the term "future proof" is very relative,the 940 is a more powerful processor,it's a quad core with 3.0 ghz clock speed and very over clocker friendly,the 720 is a tri core clocked at 2.8 ghz and also very friendly with overclocking (you should reach at least 3.4/3.3 ghz easily without adjusting voltage or cooling solutions),the only difference is that the 940 runs on the older am2+ platform while the 720 is designed for the newer am 3 platform. As far as performance goes the 940 smokes the 720 anyday however the abilty to go with the am 3 platform gives the 720 an edge since in the future when prices drop you could easily switch to a more powerful am 3 processor whereas the 940 would force you to change mobo and ram for future upgrades. As far as gaming goes both processors are good,the 720 is an awesome chip for those that dont want to spend money, the three cores multi task btter than any dual core,and its unlocked multiplier make it easy to increase the overall performance of the cpu so you wont have to worry about the cpu been the bottle neck in your case i would go with the 720 and buy an am3 board that way in the future (meaning next year lol) you won't be held back by the platform you chose and all you would have to upgrade is the cpu.