Running the "glxinfo" command will give you too much information, but in
theory what you want to know about capabilities to a tee.
What you really want to know is just which is better performing, well it's
all relative in theory. The newer card will be higher performance, ideally
less buggy, etc. Look at phoronix.com for various gpu reviews under linux
if you want to know what is best. They include historic cards occasionally
to see where yours probably lie.
Probably worth spending a 100 bucks and getting a decent low-end modern gpu
though in any regard. Memory and a SSD drive too improves any old system
drastically I find.