My vote is for the i5, myself debating a i5 or I7 860 - leaning more toward the i5 (cost vs performance) The AMD route is cheaper and that means a better GPU for better performance in games. But overall performance, the i5 is WAY better. Also 4 cores vs 3 cores (Low end amd CPU, granted you MAY be able to get 4th core working - BUt not always)
I tend to look a few years down stream, and if you can afford the i5 route - Go for it!!!
Some performance charts comparing I5/i7/AMD CPUs, You decidehttp://www.anandtech.com/cpuchipsets/showdoc.aspx?i=3634&p=11http://www.anandtech.com/cpuchipsets/showdoc.aspx?i=3641
Performance even better if you're into OC. Also the I5/I7 will considerably OC one core itself when only one core is used.