nVidia drivers come with OpenCL support built-in.  Installing AMD's OpenCL SDK is not helpful.  That SDK is made for AMD cards and will only add clutter to your machine.  You're going to want to remove that.  Also, poclbm (Python OpenCL Bitcoin Miner) does not run CUDA code, it runs OpenCL code.  You'll be selecting the platform that nVidia has set up to run OpenCL code on CUDA capable hardware.  This GUI that Kiv is writing up will have CUDA support in the future, but it only uses poclbm at the moment.  CUDA and OpenCL run fairly close to the same level of performance on nVidia hardware, but I have seen about an 8% performance benefit using a true CUDA miner over an OpenCL miner.  If this GUI gets CUDA support, I'll be willing to try it out to see if I get the same level of performance.  Mind you, I've done some tweaking of CUDA parameters to get to the performance I've got.