Cindy,
I TOTALLY cheated on this one. Go into the page where you set up the category names, and click EDIT, then change the category name so that it has a <BR> in front of it. It might look a little funny in the OSCommerce setup panel, but it displays okay on the site, and there are no conflicts I'm aware of (yet.)
It's also easy to go back and remove the <BR> if you like.
BTW, <BR> is a carriage return in HTML. So you're writing HTML into your page.
Good luck!
Mel