How to uninstall the SP1 beta

You need to uninstall the beta of Service Pack 1 before you install the final release. Here's how you do that:
Click Start | Control Panel | Programs and Features (if you're not in Classic view, this is in the Programs category).
Click View Installed Updates.
On the Uninstall an Update page, click "Service Pack for Microsoft Windows (KB 976932)
Click Uninstall.
Follow the instructions to remove the beta from your machine.