I agree with the other two who have responded - look at the .pdf creating
application. I haven't tried/used Excel 2007 yet so don't know how that one
works.
I do know that with Adobe Acrobat Professional, I've never had any problem
converting Excel, Word and many other files too .pdf format. I don't even
have to set any special switches in jumping back and forth between portrait
and landscape laid out pages.