I am always on the lookout for a small form factor PC. I have reduced the number of machines in my home down to 2 machines. Our home PC and my wife’s laptop. What I have found is that I need one more (linux) machine to do tasks. Things like email archiving, scanning, and forensics.
To make this work I have used a few options. My first attempt was to use an old laptop that had a broken display. It worked ok until it overheated (laptops just don’t stay cool). The nice part about a laptop is that is has a build in UPS.
My recent process was for a SFF machine and I purchased a Compaq EVO D51e (which is about 1foot by 18 inches x 5 inches) It is a quit running machine and has 2 ghz processor and 512 meg of ram. This works well because I swapped out the drive and added a huge internal IDE drive. This allows for automated backups via rsync.
Looking online I just found this option https://store.dataevolution.com/ProductDetails.asp?ProductCode=DT%2D7001 What a great little box.