looking for a 1 TB or 360GB External Hard Drive For My emac.
I think you'll find they're 320 Gb, but why the choice between two vastly different-sized drives? 1 Tb is a massive storage amount for a single desktop computer, unless of course you have a lot of movies and photos.
Value for money based on $/Gb tends to support Western Digital, followed by Hitachi, with Seagate in third place. With one exception, the difference/Gb is not great.
Want Something Fast, But Cheapish Too ...
Seagate Barracuda is probably your best option (but personally I prefer Hitachi). I note on a price spy website I'm looking at, that the Hitachi Deskstar 1 Tb drive has a high user rating of 8/10; the Seagate Barracuda the same at a slightly cheaper price. The Western Digital Caviar 1 Tb is about the same price as the Hitachi, but with a 9/10 user rating.
A much-recommended place to shop for good Mac-compatible hardware is OWC
http://www.macsales.com/. Not the cheapest. You can probably save yourself some money by buying the drive and enclosure separately. Make sure you get a combo USB/Firewire enclosure, preferably with Oxford chipset. Again, not the cheapest.
Another option is to operate the external hard drive 'bare' with a USB adaptor kit. That's the cheaper way to go, but no firewire.