A cost effective way to do this is to get one of the Epiphan USB Capture devices to use as a VGA or DVI input device. Attach another computer's output to the capture device. On the second computer, run something like Media Shout or Song Show or even Keynote or Power Point.

Make the background a solid color different than your text body and outline color, then use the keying feature in Catalyst Color effects to overlay the text as a higher layer.