Thanks for yor works!
But my usb hard drive can't work on my N800, the flash disk and usb keyboard works fine! My usb hard disk is 30G which two partitions, on is 10G, another is 20G. The two partitions are FAT32 system. A message "can not connect , no file system available" popped up. I also used a usb hub with separate power suplly.

Can you help me? Thanks!