Let me count the ways by which I reach such a conclusion.  It is noteworthy that others have had better luck with these people and this machine.  In some cases (e.g. WIFI limitations and multiple screens) that may be caused by the fact that most people are happy with the thing as delivered.  In others (e.g. loud and rattling fan and the hassle of an not-activated operating system), beware no matter how intense your demands of the computer..(i) The machine was shipped with Windows 10 as promised but in a version or copy that had not been activated (read not legal in the minds of the gods at Microsoft). The cure for such things is to find what is called a product key and to furnish that to Microsoft at which time, if one holds his or her mouth correctly and asks nicely, Microsoft will validate Windows for them. When USTecno (the refurbisher)  people were asked about the problem, one could sense some head scratching on the other end.  They then said that the product key was on a sticker on the machine but that one had to rub it (this is not a joke) to expose it. Don’t rub it too hard or you will destroy it (no this is not a joke either). I did rub it and was able to interpret the key and soive the problem after the expenditure of perhaps one-and-a-half hours of discovering that the problem existed (through some of my software being sufficiently smart to know that it was about to join a questionable enterprise) and what to do about it (learn how to get the product key so that I could convey it to the gods of Redmond).  It also must be said that the attitude of the people at USTecno was decidedly arrogant and rude as though it was my problem that I had obtained a machine with an invalid version of Windows.  Ultimately they would be correct in that assertion.  It was my problem and a big one!  Their attitude led me to resolve both to write this review and to never deal with them again or maybe with any other Amazon refurbisher.(ii) When I tried to connect the computer to a wired connection (RJ-45) it didn’t work. I never solved this problem (read on and know that I gave up) but I expect that the issue is the fact that the old network adapter ran well on Windows 7 and will not run on Windows 10 (know that this core machine is that old and see below). At least this problem may not go back to the halcyon days of XP as described below!  And you ask yourself how could a company ignore such a problem--and I would profess not to know short of some unintelligible comment about their competence. A possible cure is to buy a pci card video adapter, install it and hope that it works to recognize multiple monitors. Be ready to spend a couple hundred dollars and several hours of your time and then not to be certain about the Windows 7/10 problem and the form factor of the card until the big moment when you fire it up and learn the truth.(iii) A corollary to the above is that the machine is apparently delivered with a dongle WIFI connector.  Mine would only detect my 2.4 network and didn't recognize the 5.0 that I wanted to use  (my 2.4 is loaded and the wired connection did not work as previously stated).  The reason for this failure is likely either an operating system issue (this machine was originally delivered when new with Windows 7) or a process of simply buying the least expensive thing that would facilitate a WIFI claim and cover over the non-functional wired connector described above.(iv) When the machine was first fired up, I immediately noticed that one or both of the fans (It seems that the model likely has fans in the power supply and over the CPU) was/were very loud with an attendant rattling noise.  If you have ever kept an old computer for a while, you will be familiar with the sound and maybe the results. Again one wonders if the people who rebuilt the system ever turned it on. The cure in this case in part is to buy a $135 power supply (price from Amazon)  and install it yourself.  If that doesn’t sound difficult, it becomes three times more so in a small form factor machine. That does not address the potential fan over the CPU.  In any case the loss of a fan in a power supply is usually enough to produce toast.  Another alternative is of course to wait until it dies and run the risk of losing the computer and everything on it while maybe smoking up your office or home.(v) When I tried to connect two monitors to the system, it would not recognize and display on the second monitor.  It turns out that the driver in this case is very old and was originally designed for Windows XP sometime in the distant past (with apologies to those of you who may not be sufficiently old to remember such things). The problem of the video adapter not working with multiple displays is well-known and discoverable with a bit of web research except perhaps for the people who rebuilt this machine. The cure in this case is to find the right driver in the anals of intel, download it and install it. Good luck with that if you’re not a technical guru with time on your hands.(vi) And finally the ultimate insult.  Amazon policy with this particular rebuilder, and maybe all of them, is to invoke a process which consumes one-and-a-half to two weeks before one gets money back or replacement product. If you are accustomed to Amazon’s typical accommodating process, don’t be misled. This is anything but sensible or accommodating.  Amazon in this case works with these people to deliver a piece of junk and then tries to make it difficult for the customer to rectify the problem.  And this ain't a widget which is obviously bad "out of the box".  It takes work and several hours to learn about all these problems.  And one strongly suspects that further persistence would only lead to more unpleasant discoveries.  Like I said:  "Don't even think about it!".