RESOLVED:
Just change the styles to reflect below, or simply add at the end of the style.css / in a custom stylesheet:
#access ul ul a { min-width: 130px; white-space: nowrap;}
#access .menu-header ul, div.menu ul {background-color: #333;}
Setting the background color on the ULs because otherwise the shorter list items would look silly. Not sure why the original code doesn’t do this anyway. The main thing here is setting white-space, which appears to work just fine in IE7, haven’t been able to try IE6. FF3 is fine.