|Windows Live Mail has a calendar function which you can set up events with - same as Outlook. Not too sure if it will pop up without the program actually running though.|
Edit: Just noticed you already have Outlook so no advantage to having LiveMail.
Also just noticed this software in a link on this site - EssentialPIM free which may do the job.
"I've always been mad, I know I've been mad, like the most of us..." Pink Floyd