Mp3 Player (Not Ipod) With Usb

[anaxcrosswords]

Can anyone recommend an MP3 player - but NOT iPod - which can be used while plugged into a USB port?
Reason I ask is that I bought a 8Gb Sony USB 'stick' player for the car. It's great, except that when the USB cable is connected the unit is charging only, ie I can't put it in PLAY mode. I have to disconnect from the USB, so it's then relying on the battery. In normal circumstances that wouldn't be a problem, but I'll be embarking on a very long road trip in August and I'd like to have my music available all the time - not interrupted by battery charging sessions!