I had a similar problem, and it went away after uninstalling the 8.45 rpm, installing the 8.40 rpm, uninstalling that and installing 8.45 again, with reboots inserted in this procedure generously. Feels like windows...
Having another terminal to ssh into the machine under surgery helps to get around all those black screens on the way. If that's not possible, be sure to boot into runlevel 3 by entering a 3 into the boot options at the prompt.
But in the end it worked for me, and I have a widescreen with 1680x1050 and fast 3D running.
Mobility Radeon X1300
OpenSUSE 10.3 x84_64