SecretSquirrel's suggestion is likely to work, and it is also safer than dropping your monitor on the floor. Imploding glass CRTs can be hazardous.
One suggestion on playing with the geometry settings: Start with the simplest ones first, or else you may end up with a really confusing "S" shape or similar. If you do get the screen twisted into an unusual shape, I believe that the Viewsonic monitor has a "reset to factory default" option that will undo your changes.
For a windows desktop, the A90f
should look good at 1280x1024 at 80Hz refresh.