I am using windows 98 and have a C-Media on board sound card. When I try to record if line in is not muted I can here it through the speakers but will not record. If muted I can not here it and still will not record.

I've just been recording via line in and it's working great. You need to go into the volume control and select options-properties-recording and make sure that you have the box checked for line-in or external. If you've already done that you may also have to do a similar thing in the actual program you are using to record. You'll need to make sure that line-in is selected. I found that MusicMatch Jukebox is a great free program for recording from line-in. It's a pretty full featured program that can do more than record via line-in. It's at www.MusicMatch.com. It has a users guide you can print out and that helps make it very easy to use. I just recorded from a custom cassette (as a total beginner), and it worked great! Hope this helped.