Well the form factor comes into play if the machine can only support a single hard drive.
You can tell what you have by looking at how big it is, dell usually has several form factors but usually the smaller it is the harder it will be to modify.
I mean this is not a full size desktop correct?
Usually a full size desktop ranges from 13 inches big to 22 inches big.
In the PDF you attached if its the one that has room for two optical drives then it will be the easiest.
The others... well it can be done but with a few caveats.
There are four images in that PDF you linked.
Left is the biggest, the right is the smallest.
Right there indicates where you can go if you want to up your machine in the future.
Edited by MadmanRB, 24 February 2018 - 07:06 PM.