Sony NEX-5K/B or Nikon D3100?

It's Prashant from India. I'm a hobbyist photographer. I love clicking images. By the critics I got from my Facebook album, I've decided to take it a bit seriously.
I'm planing to get myself a real camera. So far I'v been using mostly P&S and occasionally some friend's SLR
I'm yet unable to decide if I like Macro more or Portraits or Nature or something else.
I really need some pro advice for my first real camera. I'm kinda short on budget.Rs.2500 to 2800/- max. (around $500 that is the starting range here in India)
I'm confused between Sony NEX-5K/B and Nikon D3100.
NEX-5K/B is much more compact and lightweight which is really good for me. Coz I love to go on bike-trips. This one will be really handy for those.
D3100 on the other hand looks more convincing. Plus no need to get the mount adapter. (which is a must if I wanna upgrade from 18-55/18-200 with NEX-5K/B)

So now you know.

I would go with the Nikon d3000 It has a better sensor than the 3100.It is cheaper because it doesn't take video, but the video I've seen from the 3100 isn't very great anyways. The d3000 with the kit lens is right at $500 USD

The NEX is probably lighter, but still a pain when it comes to changing lenses…

if you are a hobbyist, then i'd suggest moving away from SLR's or compact system…

get yourself a bridge camera - Fuji HS20 or Canon SX30 or Nikon P500…

they are good cameras and you don't need to worry about the extra lenses for your trips…