Build menu like this in drupal 7
I would use the Superfish module (http://drupal.org/project/superfish), recently this has added an option for megamenu which will allow you to build a display much like your screenshot. You will need to tweak the css to get the display how you would like it.

Demo: http://mehrpadin.net/demo/superfish/ (hover over "products" in the very bottom menu)