In the Page Setup dialog box, select the "Different odd and even" option.
You can then have different contents in left and right headers (and
footers).
To display the dialog box, click File | Page Setup if you are using Word
97-2003. In Word 2007, click the dialog launcher button (the arrow on the
bottom right) of the Page Setup group on the Page Layout tab.
--
Stefan Blom
Microsoft Word MVP
"OVERWORKED AND UNDERPAID"