Changing Menu orientation in 2010 theme

Hi, I’ve been successfully reworking the new default 2010 theme for my new site, but have hit a stumbling block when it comes to the menu.

The default is the standard hover over a button and list appears below which you then hover over and get further subpages off to the right. Great, but what I’m trying to do is to have so that when hovering over the menu option a row of subpages appear below (rather than in a column) and then subpages of those pages in a row beneath that.

I hope that makes sense and someone can lend a hand, I’ve been trying things out but not getting anywhere.

Many thanks in advance