What's the difference between Sony NW-HD1 and NW-HD3?

I found information about NW-HD3 on Sony.com
I found two NW-HD1 on Ebay.com.au

(I'm in Australia btw)

SO what's the difference? And are these good?

(I'm looking for a Hard Disk ... and good battery life. And apparently this has 20GB, and 30hrs battery life)

Any reviews out there? Pix?

I have the NW-HD5. It's a beast! 40 hr battery life and smaller than both the HD1 and HD3.

Oh, so they're all different?

HD1 - No native mp3 support
HD3 - HD1 with mp3 support and more centered controls.
HD5 - Smaller than both. +10 hr battery life. Vertical design. *drool*

Hmm ... I'm thinking between HD3 or HD5. I don't like the looks of HD5 ...