1) tell your TV to not do overscan
or
2) tell your OS to not use all the screen pixels, but to leave a border
around the edges...
sorry, no idea how to do that using X and ubuntu
maybe this:
http://www.mythtv.org/wiki/Working_with_Modelines#Getting_rid_of_overscan_and_centering_the_image
I have the same overscan issue using a LED computer monitor with a DVI connector and a DVI to HDMI cable to my Beagleboard xM. How can one set the video out on the Beagleboard? I cannot read the top or bottom or either side of the screen. I'm using the mSD that came with the board.