Really Really think hard about having a drop down menu - imo and that of 99% of all webdevelopers, they are counter productive to a fluid webuser experience.
Hiding navigation elements from your visitors is never a good idea unless you 100% have to and can't create room elsewhere.
But honestly, what bussiness are you running that needs more than 6-8 pages in a navigation menu?
I don't know a single person on the face of the earth that likes to "guess" what a website might be hiding in a navigation menu - I hate them when I see them on websites. Unless you are already at the lvl of Amazon.com - DONT use a drop down menu.