rtate,
I am no expert on streaming.
But I checked out the link for classic Q107, That appears to be a Flash media type streamer. That cannot be played within iTunes. As Watson states below, AAC, MP3 is needed for iTunes playback. you can add any broadcast using those media formats even if it is not previously listed in the Radio section of iTunes.
Though, you can send flash format audio and any sound format to you Airport Express, using a "hijacking" app- these are legal, they are just routing the audio files to your AE. On mac I use Airfoil by Rogueamoeba. This is not a free app (though a trial exists). There must be an equivalent for Windows OS. you haven't stated whether you are on mac or PC.
Some stations offer an option of WMA, Flash, iTunes, or Real format, though that is not common.
ed