Nope, the memory on the 8500 isn't upgradable or expandable. Consumer-level
video cards with memory sockets haven't been produced in almost a decade.
Note that video memory upgrades have always been a scam. Because there is no
interchangeable standard, the mfr usually charges exorbitant prices for it.
My old IBM Aptiva (purchased in 1996) had an ATi Rage II 2 MB card,
expandable to 4 MB. IBM had the 2 MB upgrade module available for $200.