Your profile indicates Office 2007, which is why I assumed that's what you were referring to. I don't have Word 2000 installed any more but, if it has the bookfold option, you'll find it under File|Page Setup>Margins>Multiple Pages. Failing that, see:
http://word.mvps.org/FAQs/Formatting...etPrinting.htm
FWIW, Word 2003 & later all have the bookfold print functionality.