Or alternatively, you have had office installed at some point on a previous
computer, you could always check that computer for software. if you have the
CD's check the version of office isn't OEM (although not likely) then you
should be able to move it from one machine to another (i.e. from previous XP
computer to spanking new Vista machine). That would be just as inexpensive

you will need to remove it from the other machine. Check in with your
local Microsoft contact centre if you have any questions.
If not then Doris's suggestion would work.
Or another option would be to get Microsoft Works Suite, which comes with
Microsoft Word. However, if you use Excel or any other Office product then
you might want to get a full "Office Suite".