I have a cheapy Ebay jobby on mine and it lowers it about 3-4c which isnt bad for something so crappy lol. However when i installed my Zalman 9700 cpu fan the hdd temps dropped about 10-15c lol so im happy
As for sound, u cud try using rubber at the sides of the hdd where it sits in the case to stop it vibrating as much, u can buy sticky rubber pads.
thats like the one i use, as u can see no miracle drop in temps but worth it.
Also, one thing to think about is the cooler takes up space in ur case. Mine basically makes my ide slot underneath my drive useless. As for a complete enclosure that will also require more room...
just found this
Mentions that even tho the temps dont drop too much, the noise reduction is good.