re-run your install proggy for the last version you installed. when you run it, you will have the option to uninstall the drivers from there. after uninstalling and rebooting, install new version.
edit- since there a many variables for each setup it gets installed to, best you can do is install and hope the new drivers improves things for ya. i believe the via site lists the changes it makes to each succeeding version, so if those changes don't affect your setup, then there's hardly a reason to make the change.