I just bought an iRiver H320 and the AC brick that comes with it is marked 5V/2A and center positive. I plugged it into the Zaurus SL-5600 and it appears to charge and light just fine. I put a meter on it that was once good, but has been repaired a couple times since it was last calibrated, and it appeared to be 5.4V with a light 10mA load (for reference, this same meter reads a brand new AA battery at 1.6V).
Just an FYI for the archives...
