Nikon D3100, Sony Nex3N or suggestions...

My wife and I are about to greet our first born in May. I figured why not ask the forum for a little guidance. I want to get a decent camera to capture some of her first years of life. I've been researching the sony nex3n and Nikon d3100. Anyone have experience with either of these? Any suggestions on cameras you recommend would be great. Budget is around $400. My wife has to be able to use it and she isn't very savvy with photography. I come from a video background so good video is important. It will probably live in auto mode and I would like to get a faster lens for a crazy moving kid.

Thanks!