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.

2) While in the module for your main menu (under module manager) be sure to check YES for "Always show sub-menu Items". It's in the module param section.

On the joomla 1.0.x series we could add new module positions on the joomla installation via Template manager- module positions (total 50 places).
How can we do this in joomla 1.5 ?

In joomla 1.5 you have to add the module positions within the templatedetails.xml