New sticks of crucial should be fine in nForce2 boards. After all the problems with their memory Crucial started using Samsung memory chips instead of Micron for their PC2700. I would not buy Crucial again simply because of the way they handled all of this. I would pick up PC3200 simply because it is not much more and on down the road you may want to pick up a 400FSB Athlon or decide to OC. Corsair is really not much more than Crucial for comparable memory and is in some cases cheaper. If you don't plan on OCing, the XMS line isnt necessary, but will get you low latencies. You can also pick up a stick of the regular PC3200 for $75 from Googlegear. I am not sure how all of this does with the nForce2. I know the new XMS3200C2 and XMS3500 works great though.
Brian