Word 2007, 2010 as viewers of .doc or .docx files
The Word integration can read and produce both Word 97 (.doc) and Word 2003 (.docx) document formats. Word 2007 and 2010 is supported for embedded viewing of Word documents at run-time. Office 365 is not supported.
I personally run Word 2013 as a viewer in a Rich Client environment with no issues, although I'm also not doing anything fancy. As far as what is officially supported, the information I provided above comes directly from the System Requirements for 126.96.36.19957 (same as 188.8.131.5256 that you mention).