hi, i've had a 9400gt for the longest time until i recently sold it to buy a used 9600gt.
yes, it CAN play it, but for comparative reasons the 9400gt is around 8 times slower than the 9600gt. maybe at lower resolutions and low-medium settings, you'll be able to play the game. but if you HAD to keep your 9400gt (like me before), and are willing to play the game normally and not high settings, the 9400gt would let you.
as reference, read this gpu ranking list:http://www.overclock.net/graphics-cards-general/502403-graphics-card-ranking-5th-time-last.html
hope this helps!