Confluence 3.x and earlier never displayed underline decoration for links, and I seem to remember a setting for this but can't find it.
Since we've upgraded to 4.2 all links have underlines and I have to manually change all styles in confluence_ist/confluence/includes/css.
I've just now upgraded from 4.2.4 to 4.2.5 and I can see this is going to be tedious every time we need to upgrade. There has to be a better way.