If you can't seem to use Response.Redirect in UpdatePanel's AJAXified callback function, add the following in your web.config file in the appropriate place:
<configuration>
<system.web>
<httpmodules>
<add type="System.Web.Handlers.ScriptModule, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" name="ScriptModule">
</httpmodules>
</SYSTEM.WEB>
</configuration>
Try now, and it works!
--
Paras Wadehra