ackcontrols :
I have upgraded a Dell Inspiron 6400 with an Intel T7600 CPU @ 2.33 GHz (2 CPUS) and installed Windows 8.1 64 bit from an OEM install disk without any difficulty whatsoever. The machine is also equipped with the Intel 945GM chipset...This machine is almost 9 years old and is still a very usable machine for word processing, iTunes, and surfing the web / email. When this machine dies, it will be like losing a friend.... I am hard to impress, and I have to congratulate Microsoft on how smooth the Windows 8.1 experience has been on a machine that some think should be in a museum.
Win8 changed the OEM rules, that now your purchase of the OS is NOT tied to the specific hardware it is sold on. That is why the OEM disk worked, only due to M$ change, otherwise you would have experienced the tried and true "this hardware is not authorized" etc. all sorts of errors / refusals from the disk.
That said, the reason most would dismiss such a ancient machine (now talking two PCs back for consumers as the life span of a normal PC is only 5 years) is due to the same reasons people change cell phones every few years.
First they are no longer under warranty and support, so 90% of the people are incapable of even understanding the difference in Wifi cards much less actually reinstall it or such to 'revive' the system. They want and demand 'light switches', just turn it on, it runs, turn it off when done.
Secondly, there is differences between what a 'off the shelf' computer does and this legacy hardware, for example you do not have USB3.0 ports, so plugging in any USB3 drive will not be as fast as compared to a modern system. These changes or added 'features' are provided because people demand it and are willing to pay for the difference.
Third COST. Modern computers were shifted to the Cell Phone model, where they are looked at as devices to be cheap, turn on, turn off, and provided a series of services. Under this paradigm the cost of PCs are now drastically reduced as compared to 10 years ago, so anyone can walk into Walmart and for only $249 buy a new PC. Considering the cost of a 'off the shelf' Windows is $179, does it seem cost effective when looking at the comparable system capabilities, warranties, etc. to refurb a ancient system as to just replace it out completely? The answer is no, it is cheaper in time, parts, etc. to just grab " a new one off the shelf" then to do all you did to your "old friend"
Lastly, if you check any of the hardware parts (DVD, Mobo, RAM, HDD, etc.) they are only warrantied for 3 years, that your on year 9 demonstrates the HIGH risk with the continued use of obsolete hardware (if it is a IDE drive for example, while everything else may work, IDE drives haven't been made in years and well you be SOL without one) that "will die" and probably unexpectantly and at the worst time, rather then that you "know due to warranty" you have three years before worrying about the life expectancy.
Congrates on breathing life into something you care alot about (old friend), and for your very narrow limited uses it seems to accomodate. Wish you good luck on how long it will last.