Should I stick with an AMD processor or is Intel now the only show in town?

I'm planning on buying a new gaming computer costing about �500 (excluding peripherals) and I'm unsure about whether to go for an AMD or Intel processor. All my previous computers have had AMD processors and in general I've always thought they were better value but Intel's new "Sandy Bridge" processors are supposed to be such a massive leap forward that I'm thinking maybe I'd be better to opt for one of them instead. Are Sandy bridge processors really so much better than AMD's Phenom range? And would it really be worth the extra money going for Intel versus getting a slower AMD with better graphics card?