Microsoft tries again to push license sales with a new proprietary fileformat .docx. But dont panic, Open Office Version 4 (to come in Q2 2008) will have an importer and until then you can convert them for free at zamzar.com

Online Tool

http://www.zamzar.com/

Offline Tool

Docx2Rtf is a freeware file converter for MS Word 2007 Docx and OpenOffice Sxw and Odt files. You do not need OpenOffice or Office 2007 to be installed for the program to work.

Word 2007 Docx files (*.docx; *.dotx) and OpenOffice files (*.sxw,*.odt) will be converted to richtext (rtf) format with partial formatting and images.

Docx2Rtf can also convert to PDF format.
http://nativewinds.montana.com/software/docx2rtf.html

found via
http://stadt-bremerhaven.de/2008/02/06/docx2rtf-portabel-dok...