I've been searching for this for a while and thought it might come in handy for some of you...
A bit of googling thew up a nice VB script available on Alan's Blog that will disable Standby on your shutdown menu.
The advantage to this is that if you have Hibernate enabled, the Hibernate option will display in its place (instead of having to hold down shift)!
Since a picture speaks a thousand words:
Hope this is useful for some of you!