9800GTX is better than a GT 240 but a GTS 250 is faster than a 9800GTX so i say go for the GTS 250 which can be found at a price range of 6-9k rs. i am selling it for 7k with the box and everything. Perfect condition. This card can run all the modern games at medium to high settings with playable settings. Games like COD 4 gives 333 fps
9800GTX is around 4-7k rs depending upon the condition as it is very old. :/
GT 240 is a low end card, i would suggest you to ignore this card and go for many others.
Hope i answered your question.