The R4 graphics are pretty much a dead end for anything other running word and excel. forget games outside solitaire etc.
Given how old this machine is, there is no real salvage and as such working towards a new platform is the only solution i can suggest.
Start with a basic mid tower ATX chassis. Find a good PSU and with the chassis you can swap motherboards, RAM and the rest of the parts. So the chassis is much more durable so it makes sense to plan ahead.