If he uses it for flight simming that pentium is holding him back. Flight sims more than any other games are held back more by CPU than GPU.
Fortunately I can liberate the E6600 from my file server if push comes to shove.
I also need to get him a case with better airflow.
So the 9600GSO is really inexpensive. Is a 9800GT a worthwhile upgrade for about 85-90$? I'm thinking probably not.