Mkay, here's a walkthru for people that want to make their own silent CD, 80 minute single track, two track 75/5, whatever you want.
First, download Audacity. It's a free/open source sound editing program that's easily available...I'm sure there's others, but this one works well for me.
http://audacity.sourceforge.net/download/
Once you've got that installed, open it up. At the top, click on Generate -> Silence. Chose the number of seconds of silence you want:
5 min = 300
75 min = 4500
80 min = 4800
Save the track as a Wav by clicking on File -> Export as Wav & chose a place to save it. Now, open your favorite burning program & start an audio CD. Arrange the tracks how you want them (if you have more than one) & burn the CD. Piece of cake. I hope that helps...if there's any other questions, feel free to ask.