Sadly Microsoft is not even remotely interested in interoperability and worldwide standards. docx is a perfect example of this.
If you can, ask people to send you the documents in a commonly supported format such as the old standard .doc format. If they cannot, or refuse to there are a couple of things you can do.
If you have a Mac, and are using the NeoOffice version of OpenOffice.org. there is a OOXML support extension available. It's mentioned on the NeoOfifce website.
You can use http://docx-converter.com/
and convert the docs to a common format that OOo can open.
Novel has released an OOXML extension for OpenOffice.org http://download.novell.com/SummaryFree. ... rjfdE4U58~
with one version for Windows and one for Linux. I've used the Linux one and it works fine. Please note the limitations of the extension... it only works on the Novel edition of OOo. It probably will not work yet on the main OOo build .
The official OpenOffice.org version 3.0 is planned to have support for OOXML built in.