Have a 55st50 which is brill for tv and movies but not for PC due to abl dimming etc and the tv generally not being very bright.
I need advise any which TV plasmas are the brightest and may not have abl.
I tried LCD tv but crap for everything else other than PC.
Your best bet is either upgrading to an ST60, which offers slightly better brightness before ABL kicks in, or a Samsung F8500 with the latest firmware. I would definitely recommend going to a local showroom with a HDMI-equipped laptop or other portable device before purchasing though. (The showroom may be able to arrange this out for you - call them and ask)