Go to Start > Control Panel > Hardware and Sound > Device Manager, expand the Imaging Devices list, right-click on the Vaio driver and select Uninstall. After that, remove the Vaio webcam capture utility using Add or Remove Programs feature and restart the computer. Now, connect the external webcam using the USB cable and install its driver. If you don't have a webcam capture utility, you can select one from Software Informer database.
Note: If you want to buy an external webcam, you can use Google search engine.