I can tell you that the silent drive enclosure works very well to cut the noise. I can also tell you that on a machine that was running for about 2 year straight with it, and a 5400 rpm drive (I forget the brand--can check if anyone really cares) it was fine... UNTIL I hut it down for about a month. Moved it upstairs where I was going to use it for an in-front-of-TV machine, and the drive simply wouldn't come back up. In frustration, I pulled the silent drive off, and did a kindof rotating shake, so as to try and loosen up the spindle (ok, I'm not that technical.. the drive simply didn't spin at all). This manuever actually worked, and has been fine since. I am concerned however, and won't be using the silentdrive in the future.
What I found, that is a MUCH better solution, is to use the newer Seagate Baracuda (sp?) IV drives. They are so quiet, you'd be amazed. Better even than a normal 5400 rpm drive in a silentdrive enclosure. And they are 7200 rpm..
Other worthwhile additions are any "silent" technology from Zalman Tech (http://www.zalman.co.kr/english/product/product.htm). I've got the video board heatsick, and the cpu cooler, which use larger external fans blowing on copper-fin heatsinks. The larger fans are about 20-21 db, vs. the smaller fans which are pretty noisy.
The fan's from quietpc are also good, and I've swapped out standard powr supply and case fans with these, with great results.
The end result is a nearly silent 1GHz PIII machine with two 60 gig drives, an ATI All-In-Wonder Radeon video board, which doesn't overheat, and is so quiet, most poeple don't hear it all all in the living room, where it's kept. I, of course, hear it, but it's *extremely* quiet! A Far cry from my other systems, where the scsi drives, and Slot 1 CPU coolers just won't keep quiet.
Hope some of this helps.. Let me know if anyone has specific questions that I might be able to answer..
-Tim
Two 120 gig Rio Cars and a few spares