I have been using Maptools with a HDTV for my games. They share my wifes laptop and its connected to the tv. They can move thier tokens around and I control the rest on my laptop. It also makes it very interactive. The other week they decided to move the beds and tables around so that it blocked off halls and doors. The fact you could grab a bed and move it made it so much more 'real'.

www.rptools.net is where you get it from, you could upload your maps and just turn the grid system on. It would not take much to adjust them to the right size.