You should be able to login using an alternate type of session.
When you are at the graphical login prompt click on the Session box in the lower left corner and select another login enviornment. If the login still hangs up you can try Ctrl-Alt-F2 to get a command line login prompt. You will then have to upgrade the driver without the graphical tools.
I have not tried upgrading the video driver on my M200 because I run SUSE using VMWare instead of directly on the system. You should be able to get video driver upgrade information/help from www.suseforums.net.
If you decide to try running SUSE in a virtual machine, VMWare server is now free and does a great job. It runs as a service so my SUSE guest starts/stops as the main systems starts/stops. I have found this to be a great way to run Linux on my tablet because I still get all the XP Pro tablet features too.