Windows Media Center on Windows 7 likes to keep itself up to date. The problem is that it even wakes the computer from sleep mode in order to do it. I sleep in the same room as the computer so I don't want it turning itself on in the middle of the night. How so I specify that I only want it to update if the computer is actually on?
Checkout http://www.avsoft.nl/Tools/guidedltime/ it is a guide time that you can set to auto update the mce guide. Set it for when the computer is normally online.