Pro Audio Support

Q:
In Vegas, and Cubase, I only get one side of my guitar/microphone recorded.
 
A:
You are probably recording a mono signal through a stereo input. Guitars and microphones produce mono signals. Try right-clicking on the track and choosing Track Properties. You can select the input here. Select the appropriate side of your stereo pair, either left or right as opposed to stereo.

Also make sure you don't have a mono adapter going into the Line-in and that you have the Left side of your sound card (mono) chosen for input in Cubase ( Or Vegas) .