Jason,
Look under the file section here under Win32API. There's a file from George Tasker that will allow you to do this.
>Could someone please explain to me the process of restricting the user to running only one instance of an application. By this I mean that once an application is running if they minimize the app. and then try to start another instance of the app. the same minimized app. will maximum. Thus, only one instance of the app. will always be running.