One's dual core and one is single core. Dual core is just beginning to really take off, and single core is going to be phased out by 2007, so at least dual core is future proof. But honestly I'd wait for the Conroe CPU's if your planning on upgrading.
yea, the cheapest x2 > most expensive D.... simply put. Intel is still a good brand, dont get me wrong, but you will definatelly notice a significant boost in performance with an x2 of some kind
Maybe he already has a mobo. Maybe he has stock on Intel. Maybe he just plain hates AMD. Go dual core and if you can/want to, go with an AMD dual core.