I recently installed this fan:

http://www.newegg.com/product/product.asp?item=N82E16835226013

A little chintzy in the hand (the housing is plastic instead of aluminum, as
the GoWesty appears to be...). But on the upside it has greater CFM and
lesser dB compared to the GoWesty model. Not to mention cheaper and *in stock*.

To install, I used JB weld to attach the original fan bracket to the new fan
housing, which maintains the same position under the fins.

It really is very quiet.