How old of a PC still makes sense to use?

Someone mentioned problems with nVidia.

Well, the Athlon64 board I am now using has a GF7300GT or so in it, and you saw the results.
The on-board nvidia thingm, though, would be worse I guess, if there's some funny business going on with shared memory.

By the way, can / should one somehow enter this kind of information somewhere, so this hardware combination gets added to the list of compatible hardware?

I had a similiar problem with a hp-laptop. I tried all but it doesn't run.
During installation it hangs and it seems, that the mouse wasn't recognized. I tried several cable and wireless mice, but all won't work.
In my case it was a too old linux-version together with the LCNC-DVD.
After I installed the recommended Linux-Mint 17 or 18 Version, it runs good, but the installation tooks much longer, than with the LCNC-DVD on an much older Atom Board.

Try this installation from the link below and I have determined, that either the DVDs I bought weren't good or the Drives have problems to read.
I prefer to burn only a netinstall CD and take all the other files from the net.
It runs much better than installation from DVD, with lots of inreadable files, that are necessary for Linux.

forum.linuxcnc.org/9-installing-linuxcnc...-or-deb?limitstart=0