Online shopping means you can't check the noise in advance.
As I mention in another post here
my X31 is silent when the Pentium M is in stepping mode, and very quiet even at full bore. The base model is $1350 US.
Its a nice machine, with a magnesium case and titanium alloy top. Excellent keyboard, though slightly undersized. My only gripe: at 30mm it is 5 mm thicker than it should be. That extra height makes it more geek-chic than svelte. 25mm would have been perfect.
If you want an optical drive and full size keyboard, as well as semi-gameable graphics, go with the T series. It's another 500-750g to lug though.