easy as pie!!
i run a panny 50" plasma 720P with a ATI x700pro, WORKS PERFECTLY!!
go into catalyst control center and make a custom resolution
trust me on this. yes, it's an odd number, but it works.
Others have the same experience...
if it doesn't look fabulous (sharp text, nearly perfect edge-to-edge coverage of the panel), use the control center to expand/contract the image to generat a new custom resolution. the one i listed should work nicely however.
i run a dvi to hdmi cable to the plasma from the x700pro