Thoughts on a new camera......

Does anyone know about SLR cameras? I have been thinking for a while now that I want to purchase a new camera but there are so many to pick from out there I don't know where to begin. I know friends who use both Nikon and Canon and they would say they like either one better so how do you know????? Here are a few I have been looking at. Help me out PLEASE!!!!!

D3000 + 18-55mm VR Lens Kit $499.95

D3100 + 18-55 VR Lens Kit on sale $599.95

EOS Rebel T3 Black EF-S 18-55mm IS II Lens Kit $549.99
All prices per Nikon & Canon websites
I'm leaning a little more on canon but only because of price and more ratings.