need a PC reminder, or popup utility

I've been diagnosed with mild sleep apnea, and I tend to wake up at the same early hour even when I stay up later than I should. (I blame it on noisy birds) Often I'm just browsing online late in the evening, and I just don't notice how late it gets. I feel ok in the morning, but after Noon I'm dragging. I'm tired all the time and tend to have trouble remembering things. I'm trying to make a few small changes to my life that will hopefully help me get more sleep.

I've decided to hook my PC's monitor up to a timer (the type people use to have lights go on when they are on vacation), and set it to turn off at 10PM. I think that will help me to not stay up browsing. Trouble is, I don't just want to be surprised by it shutting off - I need some sort of warning so I can finish up if I'm actually doing anything important.

What I'd really like is some sort of tiny pop up that will come up 30 minutes before the power goes off, and stay in the bottom of the screen, counting down, and maybe turning red in the last 5 minutes or so.

Can anyone recommend something like this? Thanks!

Try WinOff
http://www.ampsoft.net/utilities/WinOFF.php

Do you have Microsoft Outlook?

If so, why not just use the Calendar to create Recurring Events set for a certain hour every day that could even play a chime. I know it's not exactly what you're looking for but this alternative idea would allow you to remind yourself of the time at certain intervals and you could even remind yourself to go back to bed and try to sleep.