There is a Word 2007 viewer. It can be downloaded from here:
View, print and copy Word documents, even if you don't have Word installed. This download is a replacement for Word Viewer 2003 and all previous Word Viewer versions
However, I haven't installed it so I can't comment on the UI.
However, it also states:
The Word Viewer, together with the Microsoft Office Compatibility Pack for Word, Excel, and PowerPoint 2007 File Formats, allows you open Word documents saved in the following formats:
My reading of this is that you need to install the compatibility pack as well to actually read .docx files.