Tom's Hardware gives a review of Kryotech's newest model, the SuperG. They claim this new unit allows you to stablely overclock your Athlon to 1 GHz. Though the unit weighs 70 lbs, it's much quieter than previous [Kryotech] models, only slightly quieter than elevator music. It may be a bit expensive but I would do a lot for a 1 GHz computer."
Lots of pictures, lots of specs, lots of tests.