Photographers often say the world is divided into two camps, Nikon shooters vs Canon shooters, I'm firmly in the Nikon camp
The DPreview site is always a good place to start. Their camera reviews are pretty extensive but you can get a first look at some of the menus and, of course, compare specifications. They also have sample images so you can compare image quality.
The Canon EOS 1100D
scores 69 % and the Nikon D3100
scores 72 %, so there's not much difference between them. (The D3200 scores 73 %, only 1 per cent more).
The release of a new model, Canon or Nikon, always makes the previous one the 'old' one, but that doesn't mean they're bad cameras, usually it means they'll go down in price (because people do tend to buy the latest model).
If you google "EOS 1100 D vs" google will autocomplete with "Nikon D3100" indicating it's a common comparison. Here's one comparison site
(it also recommends getting the Nikon).
Personally I would also get the Nikon (not just because it's 'my' brand, but) because you write that you're new to DSLRs. The Nikon D3100 includes both a guide mode and it's got a built-in help file. I you select a setting you can press the ? button and a short explanation, sometimes even with pictures will be shown. I've always really liked that on my camera.
Finally, one of the benefits of a DSLR is that you can exchange lenses. When deciding which one to get, do not focus solely on the camera, look at the lens too. Both seem to come with an 18-55 lens but the Canon is also available with an 18-55 lens that has Image Stabilisation built-in. (in Nikon terminology that's a VR [vibration reduction] lens, so take that into account as well.
Wow, didn't mean to write an essay, hope it helps