which OS are we talking about? I think I used to do a similar thing to Psypher5. This was v easy to do in XP, and the principle is the same in Windows 7 (and Vista I assume).
You create the playlist you want run, then create a new task in the task scheduler. The task is made to 'run' your playlist at a certain time, so you just select the playlist file. Windows will automatically run it in the program the playlist file is associated with (e.g. WMP, winamp).
The final step is to right click on your newly created task and go to properties. Then,
in XP: Go to the 'settings' tab. Look at the bottom and check the "Wake the computer to run this task" checkbox.
in 7: Go to the 'conditions' tab. Under 'power', check the "Wake the computer to run this task" checkbox.
The computer should now wake itself automatically at the time you specify and run your playlist.
I'm interested to see if Psypher5's method is different from this..
EDIT: Just read Psypher's last post. Looks like the method I used was to get windows to run a playlist directly while yours is to run the program and have the program automatically play?
