Yes, finally. All you need to do it to wait for it to update your OneCare and you will have the new V2.5. Whats the changes (visually)? None. All the changes involves the underlaying layers. So its better performance and security below. In any case, you should not miss this update.
To do a manual update, which is not advisible, you will need to uninstall OneCare first. Then go download it again and reinstall. Some of your settings and firewalls rules will be lost as a result. Well, if this is the way you choose, you can start from here :