Welcome Dialog on logins

[omnipotens]

Here is what I need if anyone has any suggestions. I need either a Greeter box on login or to execute the clients default browser on login to point to a URL.  What I am trying to do in some form is to direct client logins to a URL that they will be using to access the internal systems. I would like to launch their default browser with the internal URL pulled up or a Dialog box where I can just put the URL in so they will no where the portal page is at.
Here is what I tried.

I attempted to script-security 2 system then execute the VBS but on windows 8 I would get failed running command error code 1. So then I had the bright idea of trying to execute windows msg right from the ovpn but got permissions issues as well. YES I am running the client gui as administrator.

Any ideas why I am having problems running the script or does anyone have a better solution that I have not thought of.