Help - Kick off function after Page.Load event

Hey guys, I'm kinda new to ASP.Net but have worked with regular ASP for a while now. I'm trying to figure out how to display a "processing" page after the user submits some information. Here is how I want things to work:

1. User enters data and hits submit
2. A processing page appears showing that the web app is doing some work.
3. Processing page sends user to completed page when done.

OK, the way I have things coded so far is like this:

1. On Submit, a Server.Transfer function is called to the processing page (with the form variables).
2. The processing page pulls the form variables and starts doing the necessary work in the Page.Load event. Meanwhile, an animated gif and message is shown.
3. The processing page redirects when complete (currently, also in the Page.Load event)

My problem is that once the Submit button is clicked, I never see the processing page because the work is being done in the Page.Load event and so is the redirect. Any ideas on how I can kick off the processing page AFTER the Page.Load event??? The customer has specifically asked for this notification so that their users do not hit Submit multiple times. I know it can be done but I'm sure having a hard time finding the proper solution. Thanks in advance for any help!