Not having Office on my Mac, the first .docx attachment that I received, I could open directlywith Neooffice!
None of my friends (all using Windows, BTW) had the capability to open that .docx file from older versions of Office, or with Winpad, or others. I was the only one that could open it immediately - on my Mac!
Neooffice is good...
and free! (and not MS
)