Oblivion, I don't recall ever crashing on me.  A lot more stable than games like Crysis and Starcraft 2 which seem to leak memory on my system (need to restart them like every few hours or so).
It run fairly well on near max settings on an AthlonX2 4200+, nVidia 7800GT card (probably around equivalent to a Radeon x1800xt or similar), but then, the best GPU at time of release I think was a 7900GTX.
It only really got taxing on resources in the overworld, which really looks immense (you can see distant trees and land features), so understandably resource taxing.