FireWire (based on technology originally developed by Apple), was adopted in 1995 as an official industry standard (IEEE 1394). This original version of FireWire is a high-speed, hot-swappable peripheral interface that supports data transfer rates of up to 400 Mbit/sec.
Now FireWire 800 (IEEE 1394b), the next generation of FireWire technology, doubles the throughput of the original FireWire interface to 800 Mbit/sec and dramatically increases the maximum distance of FireWire connections!
Dramatic Increase in Distance
Not only is FireWire 800 twice as fast as before, but it can be used over much longer
distances. FireWire 800 (IEEE 1394b) allows the use of various types of cabling, each offering different speed/distance capabilities. A FireWire 800 cable will connect devices up to 15 feet away, while a FireWire 800 optical repeater will connect devices up to 1000 meters (3300 feet) away!
Compatibility with Current FireWire Products
FireWire 800 provides two modes of transmission:
The pure beta mode (a FireWire 800 device connected to a FireWire 800 port with a FireWire 800 beta cable)
The backward-compatible legacy mode (a FireWire 400 device connected to a FireWire 800 port or vice versa with a FireWire 800/FireWire 400 bilingual cable)
FireWire 400 devices use a 6-pin or 4-pin connector while FireWire 800 devices use a 9-pin
connector. Existing FireWire 400 devices can be plugged into either type of port with the appropriate cable. FireWire 800 devices can achieve FireWire 800 speeds only when connected to a FireWire 800 port.
Architecture - FireWire vs. USB 2.0
FireWire, built from the ground up for speed, uses a "Peer-to-Peer" architecture in which the peripherals are intelligent and can negotiate bus conflicts to determine which device can best control a data transfer
USB 2.0 uses a "Master-Slave" architecture in which the computer handles all arbitration functions and dictates data flow to, from and between the attached peripherals (adding additional system overhead and resulting in slower, less-efficient data flow control)
To answer your question, yes it faster then USB2.0, despite the fact that USB 2.0 is a 480 Mbps interface and FireWire is a 400 Mbps interface.
The throughput numbers would lead you to believe that USB 2.0 provides better performance. But, differences in the architecture of the two interfaces have a huge impact on the actual sustained "real world" throughput
So, do you need it ?
Depends... if you are building a new daw and you would need it only for audio, i would say no, get a good internal audio card, like the EMU0404 and you will have anything you'll need.
But if you're allso interested in video, yes you'll need it, most modern video-cams now come with a firewire 2 interface.
You can read a more detailed technical article about firewire here :
http://en.wikipedia.org/wiki/Firewirek
