Not sure about Word 97, but in 2000 and 2003 go to the Footnote reference
create dialog, in 2003 this is under Insert, Reference, Footnote, on this
dialog there is a Convert button, clcik this and you have choice of
Converting All Footnotes to Endnotes, Converting All Endnotes to Footnotes,
and Swap Footnotes and Endnotes.
For 2007, just in case you wrote 97 by mistake, look under the References
tab, Footnotes group and click the little arrow on the bottom right for
further options.
Hope this helps
DeanH