Event planner, calendar, pop-ups

I would like a program where I can enter appointments at certain dates and times and then a pop-up message will appear to alert me for the individual ones. Similar to the calendar function in Outlook... but, do not use Outlook as my main email, therefore I won't get alerted. Has anyone created a program in Excel that can solve this?

Also, is there a way to keep the program running in the background (even when nothing is open)... so that I don't miss appointments?

thx!