Adding Excel .xlsx files to an ArcMap 10 document.

Don’t ask  me why but…  if you have office 2010 on your computer, you have to install the office 2007 system driver in order to see .xlsx files in ArcMap 10.

It’s a quick install.  You can find it here.

http://www.microsoft.com/download/en/details.aspx?displaylang=en&id=23734