there are several problems with this concept. for staters, I don't know of anything that will bring a system up at a specific time, unless you are talking about wake on lan, but that requires you to have a machine setup external to that machine running a scheduled process. As for the shutdown, that can be done in a number of ways.
in XP there is a tool called shutdown.exe running that will shutdown the machine. there are a few options with it like /r is for a reboot, and you can pass a time lapse for how long before reboot occurs, things like that.
You can also user the Rundll32.exe to do it. Here is a link to a bunch of functions for it.
my 2 cents on this... I'll see if I can find you some more info when It's a bit slower at the office....