Here’s the suckerfish dropdown menu for Joomla 1.5 that written by tbianco. It’s extremely easy and here’s what you need to do:
1) Create the main menu module and add a suffix to it of ‘_topmenu’. I use the underscore to so that the class name in the css is now “.moduletable_topmenu” I want to make sure in my code there is a seperation from the typical “.moduletable” and “.moduletable_topmenu”. Besides it’s REALLY bad coding practice to run words together unless you are camelCasing them. I am just used to ruby so I have using the underscore for variable names.
http://joomlatp.com/joomla-1.5-tutorials/suckerfish-dropdown-menu-for-Joomla-1.5.html