I'd go for the 9400gt.
what are you planning on using it for? none of thoswe will be gaming at high resolutions, and certainly not any modern games.
either the 8600gt or the 9400gt would be the most powerful, though the 9400 is also slightly newer tech.
I believe you are thinking of the 9500GT. The 9400GT is much weaker than the 8600GT and not a good recommendation.
@OP: I'd wait until someone from India replies to point you in the right direction as to what is really the best card you can get for that kind of money.