If you compare the beta file and the final file, there will be a few hundred MB of difference (depending on which version). That probably mean if you keep the BETA, you will be missing those hundreds of MB of patches. So my best advice is to uninstall the BETA. However, where will you get the information to uninstall? You will only get it when you manage to get to the first installation screen in the help link.
So here you are, I had copied the instruction out here:
To uninstall SP1:
- Click the Start button, click Control Panel, and then click Programs.
- Under Programs and Features, click View installed updates.
- On the Uninstall an update page, click Service Pack for Microsoft Windows (KB976932), and then click Uninstall.
- Follow the instructions on your screen.