The UpdatePanel along with the UpdateProgress control seemed to be the perfect solution. Both work just like a standard panel control that holds other web controls like a container.

These extensions are really slick, but I ran into a few issues with Response.Write. 

My code has a routine that spawns an java alert box to display any errors messages. This is pretty standard code and will display a small popup window to output your message. This is pretty much a standard way of displaying a quick message to the user.  Nothing very special about this, except that it doesn't work with the new Ajax extensions.  

   1:  Protected Sub PopErrorWindow(ByVal ErrMsg As String) 

   2:   

   3:        Response.Write("<script language='javascript'>window.alert('" & ErrMsg & "');</script>") 

   4:   

   5:  End Sub

After embedding my controls within the update panel, I started getting the following error from the Response.Write in the code above. It seems that Ajax doesn't like the partial postback that I was doing.

I talked it over with a co-worker and after a bit of Internet searching and experimenting around with code, I was able to come up with the following code as a solution. Seems to work fine and I haven't found any other side effects.  

   1:  Protected Sub PopErrorWindow(ByVal ErrMsg As String)

   2:   

   3:          ScriptManager.RegisterClientScriptBlock(Me.UpdatePanel1, Me.GetType, "Alert", "alert('" + ErrMsg + "')", True)

   4:         

   5:   End Sub

I hope this helps anyone else out there having a similar problem.