Plone 2.5 Second Level Menu

Hi there, i need a quick customization of navigation menu, using Custom Nav or the regular portal tabs. The objective is to have a second level menu that shows folder or documents in a section. Let's say the main menu is Home - Projects - Services - Info When you are in home only the firts level is available, but when you are in Project there is a second line that shows the second level of navigation under the first one. Project is selected and the content of Project folder are shown in the second level navigation. This sould work the same way for the other section. More info if requested.