Custom navigation menu bar
It sounds to me like you are looking for something like Superfish or Nice Menus.

My personal preference is Superfish, as it has become pretty damn useful in recent updates. It's also responsive if that's a requirement, and support touchscreens quite nicely.

EDIT

Something I missed (possibly another personal preference) is that I find the CSS for Nice Menus an absolute NIGHTMARE in comparison with Superfish.