I have had a lot of Linux/windows machines in the past. The best way to install Linux, and for beginners I would say OpenSUSE, is to boot a install disk.

The OpenSUSE installer will tell you what to do and tells you what the best way is to partition the drives. And best of all. It will shrink any windows drive if needed but will try to avoid this.

Now I have been running a OpenSUSE installation just by itself. And you can just update to the new version. No need for a new install.

About the yast tools. There the best. have used most of the others around and start missing YaST.

BTW, SuSE is the only one that has the nVidia drivers packaged by nVidia themselves. So Just install the drive from Yast after the installation (cant be done at a new install due to licenses) and it will activate it by it self now extra steps needed.