How to display a temporary popup

I have a page with a form that when the submit button is pressed, calls another page, but there's a 5 to 10 second delay before the second form displays.  I'd like to be able to display a "Please Wait" message either in a popup or on the page itself.  I tried using an alert box, but that requires pressing an OK button before the new page gets  called.  I checked the html createPopup method, and it indicates that it only works in IE.  I don't know how to make the message appear on the original form after the submit button is pressed.

Is it possible to make a hidden box/field/whatever visible via a java script or something? Is there any way to make a popup that will go away when the new page is displayed?  If not, what can I do to accomplish this?