Yes, the CPU is fine for most CS5 stuff. What GPU (video card) are you planning to use? While I am an ATI/AMD fanboy, CS5 is better supported by Nvidia GPUs as CS5 can offload some processing/rendering to supported CUDA capable GPUs. ATI/AMD Stream support is in the works, but not available yet.
Here is a link (Adobe) that lists supported GPUs. None of them are inexpensive. How much is your potential budget? Regardless, you don't actually need one of these to perform well. You can certainly get by with much less GPU (including using the integrated video found on many motherboards).