Invoke default browser from C#?

I used System.Diagnostics.Process.Start in the past, but if Firefox or another browser is set as the default this method always throws a terrible exception to users. At last, I come across System.Windows.Forms.Help.ShowHelp

Help.ShowHelp(null, "http://www.google.com");

Please notice that Help is a class only available for WinForms, while Process can be used for other cases (WebForms, WPF and so on).