Thanks anothercolour for the reply! I think my issue is the fact that the MBOX 2 MINI doesn't have the "Mono Mute" button. If I just mute the record enabled track, I can't monitor through my headphones. I want to be able to hear what is being sung through the microphone. If I mute the track, it prevents me from being able to hear what is coming through the microphone.
I think the "Mono Mute" on the newer models or the MBOX 2 model is the answer to this.
This post describes the exact problem I am having:
http://duc.avid.com/showthread.php?t=210336