Is there some sort of program that acts as a calendar and datebook?

I found an address book program that I never use but I assumed there must be some sort of basic date book that you can jot down things in and, at the beginning of each day, it'll let you know if there's anything important scheduled for that day.

Mozilla Calendar will get the job done.

This should work well for you

http://www.google.com/calendar/

With the beauty being it is accessible from any computer, and more powerful than anything that MS may have packaged

This looks simple enough. I'll try it out and see what it's like.