said by SoonerAl:
Lastly if you create a TeamViewer account you can sign in and access your dad's computer via a web browser (IE for example) from any computer. Handy if your traveling and don't have your laptop handy. TeamViewer also has a app for the iPhone/iPad/iPod Touch or Android device.
Is control via a web browser also free? From the teamviewer website, it looks like that option comes only with a paid account?