Have you had a look at what Creative has to offer? My brother has a Creative Zen. Holds 16gb (flash based storage, with other capacity players available), has a Radio, Microphone and the Audio Fidelity on it is better than anything else I've heard. You can also store and playback photos and practically ANY video format, the resolution on the screen is fantastic, extremely clear. The player itself weighs practically nothing and is the size of a credit card (more or less).

http://www.creative.com/products/mp3/zen/

It also has a SD HC slot so if you decide you need more space, you can pick up a 4GB SD HC card pretty cheap, with 8GB and 16GB SD HC cards slowly coming on the market as well.

As well as my brother having this, I've also owned a Zen Touch as well as my current MP3, the Zen Vision:M. Not once have I had a problem with either, and I have not been let down in any way by them.

If you enjoy audio fidelity as much as I do, then there's no alternative to Creative players as the company specialises in audio products.