The sound is out on my computer.
Unless I'm testing the sound on the control panel. That is to say, if I have it play a test sound in "Speaker Properties" off of the Control Panel, I can hear the test sound. But if I'm trying to listen to anything on WinAMP or YouTube, or anything else... I get nothing.
It's fixed now. Apparently, the quickest way for me to successfully diagnose and resolve any problem on my computer is to post a complaint about it here on LJ.