Easy to do actually,
Replay A/V offers a 'record what you hear' option which should work rather well for you.
If you want to record what's on your computer desktop AND what you're saying,
Replay Video Capture would be great for this.
So,
Replay A/V for Audio Only - OR -
Replay Video Capture for Audio AND video of what's on your screen. (How to Videos, commentary on a live poker game you're playing, etc etc)