This is a decent deal if your school isn't nice enough to give you a free/cheap distro of Vista, like mine (damn you Georgia Tech). Vista for cheap, but you'll need to verify you are currently a student/teacher/etc. For grown ups, get your kids to do it for you.
http://www.campustech.com/c/campust/title.html?mv_arg=MSN155
http://www.campustech.com/c/campust/title.html?mv_arg=MSN155