Hi guys! Actually, you don't need the Microsoft service pack like you said to open Visio files. I also checked out the Microsoft support sites and its too COMPLICATED for me because the whole page of codes etc...

Luckily, one of my fellows who are working in an educational institution recommended me an offline diagramming software: Edraw Max (for Windows, Mac and Linux OS). I'm using this latest free download 9.4 version, and surprise to find that it can open and edit vsdx and vsd files.

If you only need to open and view (without making any changes to your files) a vsdx or a vsd file, then just download the Edraw Max free trail and do that without cost. Here is the download link: https://www.edrawsoft.com/edraw-max.php
and this short tutorial video shows how it works: