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.
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.