Since my current desktop/workstation Linux box is starting to show its age (purchased in 2009) I ordered a new workstation preloaded with CentOS 7. I have been struggling with trying to bring the system up but have had a bunch of problems (systemd, no GUI available, etc.). I finally realized that I ordered a workstation but received a server.

I have a copy of the June, 2017 Linux Pro Magazine containing a Live DVD holding CentOS 7 Release 1611 (64 bit), including Gnome and KDE GUI's and other tools I cannot find on the server version I now have. I realize that I will have to download and install other tools that are not on the DVD (mySQL/MariaDB? OpenOffice/LibreOffice? Games? etc.).

Is anyone aware of problems I may encounter if I overwrite the current (probably more up-to-date) unusable software with the contents of the DVD (using the installer on the DVD)? As it stands now, I could probably get the server transformed to a workstation by downloading and installing a lot of software (starting with a browser and email program). Installing a earlier(?) version of CentOS 7 from the DVD, then updating the system seems to me a quicker and easier way to achieve that goal -- but I do not know what traps and dangers lie in wait for me on that path.

Search for yum groups (I think)...perhaps someone more knowledgeable will jump in. AFAIK, a desktop installation is a server installation plus a desktop (KDE, Gnome, etc). Groups (if I have that right)...there will be a group for the desktop environment(s), and will add anything you need to "convert" from a server to a desktop.
Look at man yum

I wouldn't think the installation you have is unusable...you just need to add the desktop environment (with yum).

There are those who'll say that CentOS is not the best distro for a desktop, but I use it because my production (headless) server is CentOS, so it helps with getting used to the 7.4 changes in a test environment.

Generally, the primary difference between a "server" distro and a regular distro is that "server" distros commonly have no GUI, as most servers sit in racks and are administered remotely; they may also come with a LAMPP stack pre-installed.

You should be able simply to add a GUI to your system, as scasey suggests.

A web search for "install GUI centos server" will turn up a number of links. This looks like a good one: https://www.techrepublic.com/article...p-of-centos-7/

Just to concur with the above, all you need to do is add the extra packages (or groups see frankbell's link).
It'll be just fine.
The repo files should be pointing at the matching repos (see /etc/yum.repos.d/* )

Adding bits from the DVD is an option, but you need to know which bits to add! At the moment, for example, you have no vector fonts. Using the approach in the article Frank's linked to is easier and you can still use the DVD if you prefer that to downloading all the extras:
https://www.itzgeek.com/how-tos/linu...using-dvd.html

I generally only use the DVD if it's either a brand new m/c or never been on the net..
Otherwise the onboard related pkgs may be in advance of what's on the DVD ...