pdf is the accepted "standard" for creating platform independent (or "meddle proof") documents
(many commercial printers insist on it)
office 2007 can do it natively ... other progs will require Adobe Acrobat (V expensive) - Foxit or (my favorite) Fineprint
http://www.fineprint.com/products/fineprint/in dex.html
there are also freeware progs (you'll have to google to find them)
however if the person at the other end is running the same prog as you (ie office) - just send it in native format