i heard that a single 9800gx2 could run crysis on max, but i don't get how because they are only 30% better then an ultra and 2 ultra's have a hard time.
DDR2 is the standard name, and describes the RAM's speed or data transfers per second. PC2, is the RAM's module name, and describes peak transfer rate at MB per second.
So for example DDR2-800. DDR2 is the standard, and 800 is the speed of it's transfer (800 million transfers per second). It's module name is PC2-6400. 6400 megabytes per second is it's peak transfer rate.
that case fan is known to be loud, might want to go with a substitute fan or not plug that one in at all (louder than an hd2900xt, now thats a shocker)