How can I make my LN52A650 volume go to zero or turn the speakers off when I want to use my surround sound? With my old TV, I could just mute it but with the LN52A650 I get a "Mute" label on the screen.

Check the setup menu, many Samsung TVs I've worked on have an internal mute feature.

I couldn't find a discreet code for this. I created sequences to both, turn off the speaker and turn on the speaker. I needed a total of four, since sequences only allow 5 steps.... Not enough to do it in one.... It's really not that hard to do, takes about five minutes or so. You have to add them to each activity....

Or you could just use the A/V receiver all the time. Easy to do since you're already using the harmony, and you get better sound.