Raven Blade wrote:...Simply give the entire, intact computer to someone who needs that system. You want to destroy an entire comouter merely because it "does not interface with new hardware"?!
Well, I respectfully suggest you give this a try. You may find it an engaging and instructive hobby. Hint: It's not nearly as simple as it seems. And the people you give it to sometimes turn out to be be quite demanding (after all of the selfless volunteer effort you have invested and delivery to their door) expecting lifetime tech support.
Back to the OP: If it can't be brought back to life, a lot can be harvested from the "dead carcass" of an old PC. Memory (RAM). Hard drive -- run DBAN (Darik's Boot and Nuke), or harvest for magnets and shiny platters that make awesome signal mirrors. Power supply: precisely 12VDC and 5VDC, though not very efficiently (and the capacitors are big enough to build your own Taser). Cooling fans (my favourite) requiring precise voltages as well (higher and they will cut out; but they will run lower, just fine). From an old desktop, endless supplies of heavy braided low-voltage wire. The lithium coin cell may still have lots of life in it. And lots of metal screws, which engage with wood and plastic quite well if you torque them by hand, gently. I harvested a giant CPU heat sink that will sit on a wood stove under a coffee pot, just to see what happens. The remainder, of course, goes to recycling.