I would really recommend the D5100, despite the specifications not being as impressive. The D3200 packed far too many pixels on a sensor that just doesn't deliver the proper results. The images I've seen on the D3200 vs the D5100 left a lot to be desired. Unless you absolutely need 24 megapixels, or HD video is a focus, I'd opt for the D5100.
The main difference between the two is that the D3200 has a higher resolution that offers better slightly color depth but the D5100 has a higher ISO boost and tends to do a little better in low light.
The D5100 also has a flip out screen if that is important to you? The D3200 is a bit smaller and lighter.
Really though the differences between the two cameras is very narrow and most users would never be able to tell the difference between the two.
Need advices (: