I run a 3650 on SL5.2 just fine.  I don't see any reason why a higher 
end card on a slightly newer revision wouldn't work, except maybe kernel 
changes.  Just download/compile/install (I'm using 
ati-driver-installer-8-12-x86.x86_64.run) the ATI driver and you can use 
aticonfig to ease the Xorg editing.

I use the following to set up dual 19" LCD monitors, primary on the left:
aticonfig --initial=dual-head --xinerama=on --screen-layout=right \
--resolution=0,1280x1024 --resolution=1,1280x1024

Cheers,
Mark

Ken Teh wrote:
> Has anyone successfully run a single desktop across 2 monitors with an 
> ATI Radeon 4300 series graphics card with SL5.3?


-- 
Mr. Mark V. Stodola
Digital Systems Engineer

National Electrostatics Corp.
P.O. Box 620310
Middleton, WI 53562-0310 USA
Phone: (608) 831-7600
Fax: (608) 831-9591