Just started recording with Sonar, and hit a major snag. I have the Audigy Pro card. Problem is, every time I want to record a new audio track, it records both the input AND all the previously recorded tracks.

So, I end up with:
MIDI Drum Track
Bass Track, which also has the drums
Rhythm Guitar Track, which also has bass and drums
etc etc etc

How can I configure Sonar and/or Audigy Pro not to record the playback tracks along with the external input??

I don't use Sonar, but I suspect you use the soundcard's mixer as recording source instead of the the line in.
That way Sonar records "all you hear" (I think it's called that with CL cards).

Go to windows soundmixer and select line in as recording source.
Probably you have to do the same in Sonar options.

P.S.: Don't use the mic in for recordings. Mic ins suck especially those of CL cards.

Make sure that you mute all other Recording sources in the Windows soundmixer window, apart from the line-in.

There's another thing that might cause it, and that's input monitoring. You might need to turn it off.

Sonar has a recording options menu that gives you the choice to overlay or replace, make sure it's not set to meld them together and that you "un-arm" the tracks that are already recorded. -if the other stuff doesn't work, that is.