Both Intel and AMD work equally well with Nvidia (or ATI/AMD for that matter) graphics cards.
Considering processor performance it really matters what you wish to do with your PC. If you value bang-for-the-buck AMD has always delivered, while Intel has usually been regarded as being a bit more stable. This is up for discussion, however, and today you are probably equally well off with either processor. Intel has the fastest products, but you pay a small premium for the brand recognition.