We are putting up four 40" LCD panels in our conference room. We are going to be driving these displays primarily from a windows workstation with a quad output video card. I need to know what he advantage would be to using something such as the Gefen 2x2 Video Wall Controller or similar. Am I correct in thinking that I would only need the Gefen unit if I wanted to hook up another source like cable or DVD and have that source display as one monitor? I mean using the PC I can span a window across all 4 monitors and just do it that way correct?