NVidia GPU programming tips are here. I just bought a GeForce GTX460 with 768 Mbytes GDDDR5to test drive CUDA and GPU programming.
Updated 6/12/2011
When I looked at the GPU specification at NVidia for my GTX460, it says that the number of CUDA cores is 336. However, cudaGetDeviceProperties returned multiProcessorCount = 7. I was wondering why. It turned out that GTX460 consists of a GF104 GPU which has
336(CUDACores) = 7(Streaming Multiprocessor Count) x 48(Shader Processor)
For More info on GeForce 400 series, see
http://en.wikipedia.org/wiki/GeForce_400_Series. For comparison with other NVidia GPUs, see
http://en.wikipedia.org/wiki/Comparison_of_Nvidia_graphics_processing_units.