upgrade advice

[grimlark]

im running a 780i, Q9450 2.66, 2GB DDR2. ive needed to upgrade my graphics card for quite a while now and was looking for suggestions/advice on which to go with. ive narrowed it down to either a 9800GX2, a 9800GTX+, or a pair of 9600GT's/8800gt's. ill be using crysis as a test and i am at a loss as to which card will allow me to get as close to maxing the graphics as possible while maintaining the highest possible fps. From what ive read the 9800GX2 or the 8800GT's sli seem to be better choices but ive also read good things about the 9800GTX+. any insight would be very much appreciated.