I'm not sure what the working spec is for distance. You can always go with a repeater as Cris suggested, since they have them for HDMI as well.

I suggested HDMI because I assumed the TVs were HDMI, plus it will let people use their digital outputs from their computers instead of VGA. That includes Macs which would require an adapter for VGA. I do suppose most Windows machines are still shipping with VGA ports - which is amazingly hard to believe.