I have a pile of external and internal drives... OWC 250, a 500 seagate and 500 maxtor runing in tandem, a 750 seagate and a 400 seagate. I also have a tangle of wires. I like Seagate, never had any drives fail, but apparently some people hate Seagates, depends on their past experiences, which can be all over the map. I also will only get FW capable drives and I wish I would have got all FW 800 drives. Moving 500GB of data takes a long time!
Everyone makes a bad batch of HDs from time to time, and hard drives can fail at any time. Just make sure you get 2 hard drives and either run a raid mirror or backup often, if you value your data. Try this test...imagine all your data on your one external hardrive gone. Can you easily live without it? If not, it's time to spring for 2 drives. At least Firewire 400.
It's also nice to be able to boot from your external hard drive if your regular drive should fail. Need FW for that. Of course you have to clone your system to the external drive, with something like Super Duper. That way there's 2 copies of your OS and everything else to choose to run from. It's very reassuring! Practice booting from the backup too, and make sure it works!
Just read a few posts like "my hardrive failed now what? Who want's to be left in that circumstance?" 100% avoidable!
I certainly like the idea of using Amazon, IF they make good on bad drives. Usually, resellers just send you to the manufacturer if there is a failure. Then you send the bad drive off and get a new one, hopefully!
Some Seagates come with a 5 year waranty, which means they stand behind their product. Of course the value of the data on the disc can be many times more than the $150 HD, or irreplaceable, so unless your data is backed up, getting a replacement for a bad drive, is not going help the problem if all your data is gone.
You must have a backup on a seperate drive, at least to get some protection. Pros back up and then back up again and store the 2nd back up off site in case of fire, flood or other acts of God (or man).
An electrical surge can fry everything and corrupt data or a virus can screw up two drives running as mirrors. Just depends how important that stored info is.