Reminder help

I'm looking for something, preferably built into XP, that will remind me of
something at a specified time and date. I tried Google with no success. I
finally tried an app (Efficient Reminder) that had a free version and said
it worked with XP. I installed it and can't figure out how to use it. I
tried several times but was told that what I was trying to do was not
permitted (in free version?). I looked at Gmail but it doesn't offer email
delivery at a specific time and date. I searched XP as best I could but
couldn't find anything.

Any suggestions? This sounds like a useful feature that should be popular.

TIA


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I love a good meal! That's why I don't cook.