Link: Calligra/Download - KDE UserBase Wiki

Based on the Open Document Format, Calligra is an effort by the KDE community and is available as a free download in both mobile and desktop versions for Windows, FreeBSD, and a variety of Linux distributions.
The Windows package installer [not yet classified as stable and so not intended for everyday use] is supplied as an MSI [good for network deployment] It can open Microsoft Office documents but cannot save back to the same format [Office 2007 format and earlier]

I tried it with a 2010 Word document and it made a mess of it. However for those who do not have Microsoft products this may serve as a viable alternative.