When I try to record screen, on the box that comes up it only gives me the choice of recording what is coming in on my microphone. How do I record Screen and record what is being output to my speakers (why it would even list my speakers as a source to record when recording the screen output is beyond me)
It wouldn't list your speakers as the source. What you're looking for is a stereo sum of all the audio signals running through the sound hardware. The availability and name depends on the sound driver, but this is usually referred to as "Stereo mix". Why are you not seeing this as an option? Well, let me take a guess: You are running this on Windows Vista? In this case, you will probably have to enable this in your operating system/sound settings first, before you can use it. Have a look at the following web page. It illustrates where to go and how to enable the Stereo Mix option before you can use it in applications: