A little trick I learned to add a pop up reminder on your Desktop on Windows XP. If you use Windows 7, see below

Windows Xp

1. Open ‘Notepad’ and create your note and save it to where ever you want but remember where you save it.
2. Now go to Add Scheduled Task (Start>Control Panel>Scheduled Tasks>click ‘Add Scheduled Task’) click ‘Next’, (it might take a few seconds to open next page)
3. Click ‘Browse’, find your note you created and double click it, choose your schedule, daily, once etc., click ‘Next’,
4. Choose time and date you want it to pop-up, click ‘Next’
5. Leave the user name alone (it should be on the correct user already) put in your password you use to log on (leave blank if your computer is not set up with a password) click ‘Next’
6. Click ‘Finish’ or if you’re on a laptop check “Open advanced properties for this task when I click finish” then click ‘Finish’
7. Click the ‘Settings’ tab, un-check the two battery options in Power Management section at bottom, click ‘Apply’ then ‘Ok’

Probably old news and most people have Windows 7 by now so follow these instructions for Windows 7. Totally different procedure but the little pop-up you get is cool

Windows 7

Follow this link to learn how to create a pop-up reminder on your Desktop if you have Window 7