It's a bit more straightforward in Word 2002 and above, where you can use
the "Book fold" option, but you can do short books this way in Word 2000.
Use the "2 pages per sheet" option in Page Setup (not the one in the Print
dialog) and then, in the Print dialog, enter the pages in the correct order
in the Page box. For example, for a 16-page booklet, this would be
16,1,2,15,14,3, etc. There is a macro to accomplish this linked from the
article at
http://word.mvps.org/FAQs/Formatting/BookletPrinting.htm
Note that all of these options are suitable only for relatively short
booklets. Although I've made saddle-stapled booklets up to 100 pages, that's
really pushing it (the outside margins become very inconsistent when the
booklet is trimmed), and neither "Book fold" (which becomes highly
unsatisfactory when you try to reprint specific pages) nor the manual method
of typing in page numbers would be very satisfactory for that many pages.
