Thanks for the input. The silentpcreview site helped. Based on that, I'm looking at these two drives:

Samsung Spinpoint T Series HD400LJ 400GB, 7,200 RPM
Western Digital Caviar SE16 WD5000KS 500GB, 7,200 RPM

Both are SATA, so I could do one of these and get an enclosure that has a SATA and USB connector. I'll use the USB for now, and switch to e-SATA later if I get a connector for that in a machine down the road. Both are supposed to be very quiet.

I used information on silentpcreview to help me purchase a quiet hard drive. It directed me to a Samsung product and I am happy with it. Recently I purchased a Samsunng DVD burner and so far it has held up also.

I'm extremely intersted in an eSATA external drive. I found this enclosure. What kind of card would I need to add to our pc's? Would this work?

You can sometimes get lucky on the LaCie site. I got a 500 GB NAS for $299 a while back when they were going for much more. I got a refurb from the outlet section.

I have a bunch of external storage at home and I've found that most brands are fine, even the no names.

Also, you can provide yourself NAS in the future w/ a USB hard drive by buying one of the new Apple Airport Extreme Base Stations. It supports a USB hard drive connection. Then any computer connected to the network can see the drive. Pretty cool. It supports USB hubs so you could just keep adding drives whenever you need them. I have mine next to the router and DSL modem in the closet, so noise isn't a problem cause it's out of sight. Access times are pretty good too. I've archived videos, photos, and many large files w/ no issues. It works w/ the new 802.11n wireless standard and can conceivably go over 130 Mbps, faster then your normal wired connection. Though you need 802.11n on your PC side too.

Spiff, there are a bunch of enclosures that do ESata and USB here

They're in the $30-$50 range. I'm trying to figure out which one looks good, so I have the ability to do esata down the road. Only USB for now.

I need eSATA and firewire. USB will be too slow.

Correction to the drives I am looking at:

Samsung Spinpoint T Series HD401LJ 400GB, 7,200 RPM
Western Digital Caviar SE16 WD5000KS 500GB, 7,200 RPM

Notice the Samsung is now a HD401LJ, not a 400. Difference is 16MB vs 8MB cache buffer. 401 just came out in November. I'm leaning towards that one at this point. Now I'm looking for a good enclosure for it that supports ESata and USB. Don't need firewire.

Still looking. It appears that Samsung drives are quieter and run cooler then most, but give up a little speed to do that. WD seems to be quiet if you avoid the raptor line. Not finding much about Seagate and Hitatchi yet as far as quietness goes.