Thanks for the detailed response. The requirements are that :
1. Users are given a pop up stating that an upgrade is about to begin
2. The program is upgraded
3. Users are given a warning that the machine will be rebooted
4. The warning should have a counter that displays the amount of time remaining, and then reboot at the scheduled time
5. install another package after reboot.
I did find a solution, and this is how the task was accomplished:
1. Used "Install can request..." from Advanced options to enable display the first message
2. Created a VBScript code to warn the users and display a counter, and reboot at end of counter
3. Copied all extracted files to a temp folder (as the files may disappear from c:\windows\softwaredistribution\download]
4. Added the next setup program which is to be run after reboot to HKLM\Software\Windows.... RunOnce key
5. Within the setup program, added capability to delete setup files from temp location at wend of execution.