Hi NvdB,
I am not with Laminar Research; just a flight simmer.
You were lucky in getting X-Plane as a gift.
Firstly have a look at the following link found at https://www.x-plane.com/kb/x-plane-11-system-requirements/ Many X-Plane users purchase a system with the recommended requirements for best impact. What you build will depend on finances. If you do purchase a new PC, for a better performance use an Intel CPU and a NVidia GPU. If you purchase an off-the-shelf system from your local PC shop make sure it is a gaming machine. The specifications don't make mention you need good cooling in the casing. X-Plane 11 is resource hungry and generates heat from the CPU and the GPU. This heat has to be removed otherwise your system will crash.
Although X-Plane is developed on an "Apple" or "Mac" system by Laminar Research, they recommend a Windows based system for best performance.
Because you have a DVD set you will have to have Disc 1 installed in the disc drive at all times. It substitutes for the password key which is supplied with the digital download version. So if you purchase a new PC you will need a DVD drive as part of the machine or attached as a portable drive via a USB connection.
Provided you have installed the disc version in total as a stand-alone directory ie not mixed up with other operating system files etc on your old machine, all you need to do is copy to a suitable capacity portable storage device. It should run from this device. A USB stick can cause a problem. If you purchase a new PC then copy from that portable device onto your new machine. But you will still need a DVD drive to run the software. If you don't have a dvd drive you will be restricted to the "demo" mode which has a time limit and a location restriction.
As a side issue many of the boxed DVD sets have a password key enclosed with the package. This key will not allow you to run X-Plane. It is a "scam", "conn" or "ploy" to get you to purchase more of their products at a reduced rate.
Good luck and welcome to X-Plane.
Glenn