If you want to find a variety of QUIET drives specifically tuned to reduce noise and to stream data efficiently check with weakknees.com. They are focused on TIVO but their drives are quiet, reliable and tuned to order.
Be aware the Seagate 500GB SATA (ST3500630AS) is the noisiest drive I have heard in my life. Just read the reviews about it on the newegg link. The spindle motor is silent, it is the seeking that is noisy. True story: my Dad was within vicinity of my new build and commented it was raining outside and I said, "no that's my hard drive!" The other thing is Vista seems to always be busy accessing the drive so it is somewhat constant. This would definitely not be the drive for you if you have a machine on the desktop or are going for an ultra quiet build. I would recommend reading all the newegg reviews for the drive before purchase.
Another thing to consider is some drives like the Seagate mentioned above do not do native command queuing (NCQ)! I would have thought any big, new SATA 3g drive would have it and got burned when I found out it does not.
Because I have such high regard for Seagate, I got caught with my guard down when I quickly opted for their drive.
I've disabled all the indexing on my hard drives on Vista. I'm not the type to be constantly looking for lost/misplaced files so this is a feature I don't use. Less access --> less work --> less noise.
Vista 32bit | Core 2 Duo E6600 | BFG GeForce 8800 GTX | Patriot EP 2X1GB PC2-8500 DDR2-1066 CL5-5-5-9| 3ware 9650SE-4LPML RAID Controller with BBU | 150GB Raptor x2 RAID 0 - OS | 150GB Raptor x2 RAID 0 - Data | 150GB Raptor - Swap/Backup | SB X-Fi XtremeGamer Fatal1ty Pro Series | Dell E207WFP & Samsung SyncMaster 213T | Asus Striker Extreme | PC Power & Cooling Turbo-Cool 1KW-SR | Silverstone Temjin TJ07 | Zalman CNPS9700 NT
No HDD will ever be quieter than a SSD. No HDD will ever match the performance of a SSD. Unfortunately, SSD's storage capacity is still quite limited in comparison but if you get a 32GB SSD for your OS and applications (using a HDD for storage) you'll be golden. For the storage HD, no need to go crazy. Get something that will run quietly and last long. I prefer Seagate.