What GPU will you be using? I know you said you won't be playing any new/high-end games, but if you're just gonna be using integrated graphics either on the new AMD APUs or the iGPU on the Sandy Bridge Intel CPUs it won't run any games on max settings really, even games that aren't very recent. I'd be pretty surprised if the APU (the stronger of the two) could even run a game like Fallout NV decently :x.
But yeah just get a decent mid ranged AMD processor (APU if you're not getting a discrete GPU), 8GB of RAM (2x4GB kits are like $50-$60 on NewEgg now, 4GB probably won't run 4-6 bots very smoothly either) and for botting the GPU honestly doesn't matter.
Also, GPUs that are within a decent budget and will serve you well (since you're not doing any hardcore gaming):
GTX 550 Ti
GTX 460
GTS 450
All of those can be bought within the $100-$150 range.