I am not clear on what I need to do to upgarde my WSS SLK site from 1.3.0.1 to the latest 1.3.1

The current site is up and running, a couple of courses are already in use on it. Can I upgrade without disrubting existing assignments?

I downloaded the the Upgrade to 1.3.1 zip file, I know there is a database upgrade script and a web part repalcement script, what else, do I first install the full 1.3.1 version?

Sorry if I have redundant or seemingly simple questions, but I don't want to mess up my existing site with the upgrade.

Thank you for the help.