RadarSync is now fully compatible with IE7. When you first install the plugin, you will be asked to confirm the installation. You also may see a yellow bar at the top of your browser, asking you to confirm that you accept this "add-on":

Click to accept, and continue with the installation, accepting all of the various confirmation requests.
Note: Although IE7 indicates that the RadarSync file is an "ActiveX" during installation, it is not --it is a plugin file (which is much safer than Active X). IE7 simply does not distinguish between ActiveX files and plugins for some unknown reason....