The problem with the BIOS wakeup is that it has no concept of weekends. I wrote a Windows program for our company that automatically shutsdown or switches on your computer once or twice a day and the user can set different times for each setting (i.e. 14 on/off settings, 2 on/off for each day of the week). You can also set it to switch on on a certain date for when you are away on holiday and want it on when you come in.
This lets the computer add updates etc. before you come in but remain off at weekends.