Compact System Camera Recommendation

[salmon]

I'm looking to get a new camera having been impressed by the difference between my friends Olympus PEN and my cheaper Lumix compact. I like the idea of on the compact system cameras as I think a DSLR would be a bit large for general use but like the idea of interchangeable lenses. I've had a look at a few, like the look of the Nikon J/V1, Sony NEX-5 and Panasonic GX1 or if to up the budget to say a Sony NEX-7.

Any advice appreaciated as I know very little about photography!