The NetGear MP101 can not be autodetected. You must specify the device type as MP101 in the server settings.
The NetGear MP101 will not play back APE files compressed to insane level converted to MP3 format. The insane compression takes too long to decode and the player refuses to play it. See this thread for more details.
The MP101 will not function correctly under Vista. Short files will play okay, but playing a longer file will not continue on to the next song. The problem seems to be in the MP101, though how this can happen is unclear (it works fine with XP). The MP101 will not ask for the next song, it is not a firewall issue on Vista's side.