I'm using SuSE 8.1 Pro as well, and I tried both:
installation via src.rpm, and installation with rpm via yast2.
Both worked well, but I had to reinstall the driver, because I set up a new Linux in between. So I did the yast2 prodcedure as following:
*installed Suse 8.1 from DVD with "nv" default dummy driver
*clicked the 4191-kernel.rpm - installed with yast2
*clicked the 4191-GLX.rpm - installed with yast2
*edited the XF86Config according to the manual
I recommend you try the easiest way first, unless you have anything other that the default Suse 8.1 setup