I'm investigating some options on a removable storage device where I can plug into my router directly without going through a computer first. I just want something that I can put all my music and movies to and do backup on. I suspect 300Gb to 500Gb will be plenty.

I'm not too keen on having only a USB or a firewire device because my router doesn't have that interface. As I also don't have a spare computer lying around and the one I use most of the time is a laptop, I don't want to be tied down to a desk when I use this device.

Any recommendations would be appreciated.