Greg -
I prefer a different method, something that I first used while teaching at Computer City a long time ago. Each table has two students with a computer, monitor, keyboard, mouse. On the table between the two monitors is a third monitor that feeds from the instructor's monitor. I realized several advantages with this:
Instructor doesn't turn down lights to see projected image on the board in front (great for students to scribble notes).
Students with bifocal glasses don't get neck strain from extreme up-down nodding of the head.
There is a sense of immediacy and convenience as we go through the day.
Cheaper than computer projector (and lamps).
Disadvantages:
The little box that splits and reamplifies the video signal from instructor is (in my opinion) very expensive.
Extra cabling hassle.
Your idea _may_ get a negative reaction from the students when you take control of their PCs from remote.
Just a thought.
Al Hedstrom