Go with the 2x 9600GT
better performance, and still cheaper!
The 8800GT is a good buy right now - its slightly more expensive than a 9600 and its still slightly more powerful.
your choice.
Frankly i dont suggest getting a 9800GTX, its hardly worth the money seeing out 2x 8800GTs beat it. Not to mention 2x 8800GTS's
especially since the termination date is absurdly close for 9800 series already - sometime in June i belive. thats when Nvidia may release 9900, so ive read.