yeah the D5100 is a better deal if you aren't too picky. If it got the same sensor as the D7000 (which it seem) then it is better then the Canon in low light and higher ISO.
Well the D7000 vs D5100
6fps vs 4fps: advantage d7000
Fixed screen vs tilt: D5100
Maganisum body vs. plastic: D7000
More manual controls vs menus: D7000
1080p 24fps vs 1080p 30fps: D5100
Sensors: tie (if it is the Sony cmos like the D7000, D3100 used Nikon Cmos)
Lenses selection: D7000, the D5100 still lack th ebody motor for older Nikkor lenses.
Nikon CLS wireless flash: tie, both have it I not sure if the 3100 does (for speedlight without buying a trigger and using i-ttl off camera).
39 vs 11: D7000, but I only use the single point focusing (like manual on the camera) so no really advantage unless you do thing fully automatic. Or focus and recenter, same thing.
All in all the D5100 is a better deal for consumer. For enthusiast the body and control of the D7000 is much better and faster to change settings to get a good shot.
The d7000 defaults were soft and designed for portrait. You have to use the submenu to jack up the sharpness and contrast to look vivid on the D7000 to look like the unnatural Canon defaults.
AF-S DX NIKKOR 35mm f/1.8G: Not a wide angle lens, but for the price ($200) you really cannot beat it for speed (f1.8), weight, and sharpness. I have much more expensive lenses but the 35mm lives on my camera body at least 50% of the time.
I believe that any newer nikon lenses that have the AF-S designation will work with the D5100. It is my understanding that the D5100 camera body cannot focus the lense itself so it relies on autofocusing lenses (AF-S) to get this done. You may want to investigate this further though.