Even though Intel's clock speeds are faster, AMD will perform just as good if not better. For gaming I would go with an AMD 64 3200 or a 3500 if you have the money. However you will need a good graphics card to go with it.
AMDs may be better for gaming, but, that doesn't mean that you're gonna get terrible performance out of an intel. But if gaming is your primary concern, go with a 64-bit AMD.