The AMD is approximately 30% more powerful than the Intel according to passmark's benchmark. Personally I would go with the AMD, but hell, if this is for a new build just go for a newer CPU generation?
They BOTH are HORRIBLE for Gaming. On my old PC i have a Intel Pentium E5700 with a AMD Radeon 6770, it gets below 30 fps for Bf3 on medium (1280 x 1024). It is alright for low requirement games (Crossfire, CSS and etc.) but for mid-high end games i wouldnt get either. It even struggled to run Dota 2 which uses the "source engine". And it was the CPU bottlenecking, my friend has an Intel i5 2500k and an AMD Radeon 6770 and can run BF3 on high (1920 x 1080) at 40-55fps.
But if you had to choose i would get the AMD one, why? Because you can upgrade it in the future if you have AMD 3+ mobo.
CPU: Intel i5 2500k
MEMORY: Gskill 8gb 1600mhz (4gb x 2)
MOBO: Gigabyte GA-Z68X-UD3H-B3
HDD: OCZ Agility 3 (60gb) and WD Caviar Blue (1tb)
GPU: HIS AMD HD 6950 (x2 crossfire)