What's the best windows based way to make a 2 screen video

I want to make a video with 2 screens in the final output
1 is the desktop of a software demo
2 is a live video webcan of me explaining the sowtware

I'm using logitech web cam which works their new Logitech capture software.
It produces videos taht are very hard to edit with sony vegas
Is there a better solution or a much better finbal editor than sony vegas?

thanks
george