just incase you are upto trying latet driver under ubuntu...
try installing it this way..
download the .run file from ati..
right-click on it and select properties..
check 'allow execution' under permissions..
rename that file to ati.run
open terminal in the same folder/directory and type
./run
now the installer GUI will start...
chances are that none of the text and options would be visible/readable under ubuntu...
so select the option Tab on the right side on all pages
after installation...
type
fglrxinfo
in terminal... note it..
reboot.
type
fglrxinfo
in terminal... note it and post it here..
in terminal...type
aticonfig (or sudo aticonfig)
if you get any error..then catalyst is not installed properly...
if you get a help file regarding arguments to aticonfig command then its probably installed properly.
sabayon would work well with your display BUT you might have to compromise and settle to 24bit resolution...something that happened with me.
if you are keen on trying new OS then mandriva can be a good choice to try.
check this link :
DistroWatch.com: Put the fun back into computing. Use Linux, BSD.
you can check many distros for their support regarding hardware..how consistent have they been regarding software support and all...and then decide which one suites ur trial needs
btw you have already tried most of the top distros...just choose one and work towards it...