There is something else that you can try...
These settings are for an LCD screen, but they may help on your plasma...don't worry too much about the 'brightness and color' settings, but pay most attention to the hookup details (using HDMI2 etc...)
http://www.operationsports.com/forum...-demo-try.html
I recently had to replace my old 50" rear projection lcd HD TV which had no perceptible lag. I ended up getting a Samsung Plasma that has a little bit of lag (it also has Game Mode which helps a little). It's hurting my hitting a little bit, but I think I'm adjusting. Compare that to my 40"Samsung LCD in my bedroom that is unplayable for MLB even with game mode on...
I too wonder if more game makers will start including 'calibration options' like Guitar Hero does...would be nice.