The calendar reminder pop-up feature is no longer available in Windows Live Mail as it was in Windows Mail (Vista). The reminder alerts are only sent to the email.
However, you can install this windows calendar and it shows the events reminder between selected time intervals.
Extract the folder and copy it to C:\Program Files and run the setup file.
Hope this helps.
Please reply if you have any further questions.
Thanks and Regards,
How do I get events from windows live mail calender to pop up ?