WinAlarm is a freeware reminder and alarm program. You can use it to remind you of specific forthcoming events, or of events that recur on a regular basis. It provides a customizable pop-up color-coded window bearing whatever text you enter, plus a customizable sound (if you want one). It can also provide advance warnings, and after-the-event reminder warnings.
WinAlarm requires Windows 98/2000/Me/XP/2003.
Download: WinAlarm 2.2.2