Those people considering running faster code should consider using GPGPUs. Advantages of GPUs are that they have many more cores than CPU. The disadvantages are that the communication between the CPU and GPU is slow and memory management is tricker. Thus there is no guarantee that code will run faster when using GPUs. CUDA is a set of extensions for C which will allow you to access hardware accelerators (certain NVidia cards in this case). CUDA has been around for a while and there are CUDA libraries for FFT and BLAS. I have not used cuFFT myself, I know that its APIs are based on those of FFTW. The capabilities and ease of use of these cards are improving with each generation. If you are in the game of speeding up your FFTs then I recommend you take a look.
Adam
