It doesn't really matter what brand of CPU you get. Both AMD and Intel sell CPUs that'll play those games, and also sell CPUs that won't play them.
For example an AMD Phenom 955 would play those games no issue while an AMD Athlon is going to have a number of issues. Its all in the price - AMD Phenom $150, AMD Athlon $100.
My suggestion would be to get an Intel i5 2500 for $200. Or if you don't have that much money get an AMD Phenom II x4 955 for about $150.