Nikon has the best low light handling in the biz, by the way, and the Nikon D3100 is a GREAT choice. +john ishol
the reason people buy Nikon is great glass, superior low light handling, and a LOT of people like the layout better. Canon makes a fine camera, but to imply that cost is the main reason people choose Nikon is disingenuous. Also, the D3100 is great because it takes the exact same picture quality as the D700 at pretty much 1/2 the price. It just lacks some of the features, such as screw motor, and has a little less advanced low light management. All in all, the Nikon is a fine camera that'll last for YEARS of use. And at a couple ghundred more, the D5100 is nicer if you're getting advanced.