"Best idea is to install your production software on your production machine, get it all working properly and never update it or even connect it to the internet."
I don't think I agree with any part of that statement. A test machine would be a production machine, normally the Design Manager. You need updates, usually they resolve problems that being experienced in the design packages. The internet is a valuable resource for research learning, supplier and community parts, etc. Employers that overly restrict access for viewing sites and downloads are tying designers and engineers hands being their backs and expecting them to be even more productive. Bad management. If a design team has a lead designer or manager that knows what they are doing any and all issues can be resolved w/o issue.
Windows 7 is great, I don't have software issues unless we are trying to run really old software, such as COSMOS DesignSTAR 4.0 or AutoPIPE 2004. I agree with mcgyvr, subscription is the way to go.