The firmware file came on the player's flash memory. It looks like the HZ520. I found this web by searching for that model, and found a picture of it.
http://www.obit.cn/pr/product_show.asp?id=221
Here are some pictures of it, in case it helps you recognize the firmware:
Date: 2007-10-16
Ver 01.08.1653
mmm, then it should have the 2608 chip... and that firmware I uploaded isn't the right one... Well, I'll just wait until there's some New Rockchip Firmware Extracting application before messing up with the player...
Thanks!