contentwhores on "Preventing a sub-page from appearing in the drop-down menus"

Hi,

We're using a pretty simple theme at the moment, one that doesn't have drop-down menus. We want to switch to a new theme like Enterprise which has drop-down menus; one item for each parent page, with all the child pages appearing as menu items. However we want to hide one of the child pages - i.e. prevent it appearing in the list of drop-down items. Any ideas how we can do this?

Thanks!