There is this particular software form Lifsoft called Auto Poweron & Shutdown
http://www.lifsoft.com/,
using which you can do lots of scheduled tasks like:
Shutting and restarting the computer at predefined times,
Automatic waking up from Standby or Hibernate mode,
Starting and stopping programs as and whe needed,
And as you said it can play audio files which can be used as alarms.
and lot more.
Using this you can wake the computer from standby or hibernate mode in the morning and play a music. In this way, too much power is not used up in keeping the system on all night.
