I have a Windows Server 2008 home server, that i'm going to sleep during the night. It's BIOS does not support scheduled boot. Can i use some kind of task in the Scheduled Tasks to make it sleep at 10PM and wake it again at 8AM in the morning?
The fact you can't find an option of scheduled boot in the BIOS does not mean it does not support it.
It's BIOS does not support scheduled boot. If you mean by that it does not have ACPI (Advanced Configuration and Power Interface) hardware support then there is no way to make a schedule boot (other than the WakeupOnLan Tanner suggested).
Well... there is always the way of putting a timer on the power-cable :)