Move wordpress install to subfolder

I've installed wordpress in the root directory. There are many modules and configurations so I would reather not reinstall and start over... With that being said, what I would like to do is move the installation to a subdirectory named demo so that it can be called at demo.domain.com.

I read an article at http://smallbusiness.chron.com/move-wordpress-root-subfolder-52605.html but that article doesn't have a date so I don't know if it still applies. Can you tell me if I should follow those instructions or if there is a better way.

Thanks in advance.
Jim