Take a look at our forum at
www.vulcanriders.us/forum/
You'll find that the threads are not underlined, until the mouse is over them. It looks a lot better, is a lot cleaner, and is the way it should be working, even if it's not doing that in the stock version of vBulletin.
Even Microsoft Windows, in stock form, does not underline the icons until you click on them, and has the option to only underline them on a mouse over.