I recently built a dual boot Suse 9 / win box.

Suse 9 would not allow me to install the nvidia drivers so I've pulled that card and am probably picking up a Radeon 9800 pro tonight.

Will this work? Will Suse auto detect this or will I have to do something?

no, no linux will auto detect it. but you could go to www.ati.com to download the latest driver and install it which i believe was 3.2.8 and i got my radeon 9600 pro work right. The key was that if you was using a new kernel or new compiled by yourself, my was 2.4.22. Please disable the DRM module support. that will kept you from getting your card working forever. Second, use the internal /dev/agpgart first. then restart. go use "/usr/bin/redhat-logviewer" while you are using probably VESA for your radeon to see if there is some error about fail to initialize driver modules... If there is, then do "fglrxconfig" again and use external /dev/agpgart. after that, you need to add "/sbin/modprobe agpgart agp_try_unsupported=1" and "/sbin/modprobe fglrx" to your /etc/rc.local file. if might not be this file, because i am using redhat9.0
But what i am trying to tell you that was it works on linux if you have M, module for radoen card support and DRM support off.
You could use "glxgears" to test your card. if it goes around 3000. then it's working right.

Please see my post here
The SuSE drivers are in fact ATI's drivers but with some SuSE configuration. You need to km_frglx.rpm because this module is missing in the SuSE kernel. Follow the directions and you should be set.