Andy,
A potential feature for your consideration is to build the following script into the menu. It essentially prevents a user from selecting - highlighting by draging with mousedown as if to copy - (accidently or on purpose) the contents of a page, etc. It may be somewhat more relevant with the use of the header menu items that some folks may try to repeatedly click or mouseover and inadvertly select. The script just avoids the ugly look of items being selected: