Goodness knows why anyone would use MS Office unless it was bought for them by their company.
OpenOfficeOrg is file-compatible with MS Office, has all of the important features and most of the unimportant ones. It runs on Wintel, Mac, Linux (x86 and PPC) and is free.
The only real missing feature is a database with visual reports comparable to those in Access, but if you pay the nominal fee for SunOffice, you get the Adabas database.
It's certainly about time people stopped paying £100+ for the privelege of reading bloated MS-Doc files.