When you say you want to pass the user name and password to another application, do you mean a web application.

If so then look at the log on page of the target application. It is most probably submiting the username and password to an url. Now if you look at the source, you should be able to get the nameo of the username and password field.

Now you can simply call that page like

[assume that the target application's form submits to open.asp]
response.redirect "open.asp?Username='someusernasme'&Password='somepassword'"

Hope this helps.

Danial