Dolby Digital 5.1 out of an iBook?

[Alric J. Lam]

Hello,

I have a 600 iBook that I've recently figured out I can hook up to my home
theater system using a PClink I had left over from my MD player setup.  the
PClink translates USB to optical out, so basically I plug the USB into my
iBook, and the optical to my receiver.  Only thing is with a movie that
definitely has Dolby 5.1 surround sound, my reciever only will play it using
Dolby Pro Logic, making me thing that the optical signal is still only 2
channel.  My question, is there any way to get my ibook to output Dolby 5.1,
either with different equipment or different settings?  Or is it a limitation
of the DVD drive, or hardware?  

Thanks!

Al