Canon EOS 550d (Rebel T2i) vs Nikon D3100?

The thing is I'm Really into photography, but I also like filming, and want a new camera. I'm a nikon user myself and although my main focus is photography, I would like to film, and I'm a bit skeptic about the built-in mic in the D3100 because of the wind noise, so I would really appreciate any advice on that.

Added (1). And how hard is it to control focus while filming without AF

Http://www.dpreview.com/reviews/sidebyside.asp

You can do a side by side comparison to help you with your decision making.

You really have to look at the Nikon D7000 to use an external stereo microphone.

Since you are a Nikon user, switching camera systems will cost you more than the additional cost of the D7000 over the D3100.

In any case, only the two Nikon's can can auto-focus in the video mode.

You do know, don't you, that most of the sound in videos produced by video production companies, is laid in later in post production

Here is a sample of such a video made with a D7000