In any graphics type environment (e.g. gaming, visual simulation ..... etc) it is very important. I'm not an expert, but from what I understand, in a modern computer, the GPU is usually much faster than the CPU. To digress, lots of software developers out there take advantage of this and harness the power of the GPU as well as the CPU. Modern GPUs have a type of parallel architecture known as CUDA (Compute Unified Device Architecture). So GPUs are like little multicore chips that are not only designed to deliver lightning fast graphics to the screen, but (depending on the software and if harnessed correctly) also greatly speed up the computer in general. As one molecular modeling software team puts it (http://www.ks.uiuc.edu/Research/gpu/):
"the fastest GPU algorithm achieves up to a 125-fold speedup over an optimized CPU implementation running on one CPU core"