Analog speakers like yours are never detected. One just "tell" the system that we use 2.1 speakers.
2. Not all media center PCs include a TV tuner.
Without details I can only write "so far, so good."
I just set up a new Gateway Media Center system. I plugged in my speakers to the line out port. It is one mini stereo plug that goes to two desktop and one powered subwoofer speakers. The audio is resident on the motherboard. The speakers play the system sounds but when I open the Media Center, it does not see the speakersand will not let me set up the TV viewing. Help??? Also, is the OS set up to watch TV on the system VGA monitor or only on a separate TV?