I apologize in advance if this issue has been discussed elsewhere in the forum, but I searched and couldn't find any info specific to this:

Basically I am trying to stream music from iTunes on my PC to a stereo in another room, but I get an error message in iTunes that says "Remote speaker is not compatible with this version of iTunes" (currently I have iTunes 7.4.2).

My setup is: my cable modem is connected to an airport extreme through ethernet and then the extreme is connected to my PC through ethernet (PC doesn't have a wifi card). I then have an airport express in a separate room to connect to my stereo.

I have no problems (that I can see) networking the extreme and the express. They both show up in the airport utility and seem to be working fine. I have them setup on a WDS. Now I'm somewhat computer literate, but not when it comes to networking so I'm sure I either have settings configured wrong or equipment hooked-up wrong. I've tried to research this problem online but couldn't find much info. What little I have found leads me to believe that my iTunes is not being allowed to communicate through the AP extreme onto the express, but I'm not really sure what the real problem is.

Can anyone please help me understand where I've gone wrong with this?