eSATA stands for External Serial ATA. It's built on SATA, the current standard for hard drive interface (if you open your PC and see a small red cable attached to your hard drive rather than the flat ribbon, that's SATA). In actuality eSATA is exactly the same as SATA. A motherboard manufacturer gets to put a fancy sticker on it's box and mark up the price a lot to add a SATA port to the I/O panel in the back.
In any case it's faster (because that's what technology does after all, just gets faster and faster)
Since I'm such a geek, I'll provide for you the data transfer rates:
USB | 480Mbps (burst) |
Firewire 400 | 400Mbps |
Firewire 800 | 800Mbps |
SATA (first gen) | 1200Mbps |
SATA (current gen) | 2400Mbps |
SATA (next gen) | 6000Mbps |
If you have a home network the best way to go is to get an external hard drive that supports ethernet (commonly referred to as NAS or Network Attached Storage). That way you can access the hard drive from any PC on the network without physically moving the device. It can get pretty kewl if you're roaming around the house with a wireless laptop, streaming MP3's from your network storage drive. Max transfer rates on a NAS device would normally be 800 Mbps, unless you get one that supports gigabit ethernet (8000 Mbps).
By now your brain should be turned off. Time for a beer
