FireWire is USB's main competition because of its high speeds and hot plug and play ability.  FireWire controllers are capable of digital video compression features that can translate analog broadband audio and video signal into digital PC data. 
A few years back, Apple Computer teamed up with other big names in consumer electronics such as JVC, Sony and Texas Instruments to develop and market the FireWire technology.  Since then, it has been in fierce battle with USB to try and satisfy the user's cravings for high speed and ease of use. 
USB 1.0 and 1.1 were both capable with either 1.5Mbps or 12Mbps, but FireWire's technology jumped to a standard up to a whopping 400Mbps.  Since then, USB has developed its latest version, 2.0, which is capable of going up to 40 times faster than its previous version, totaling 480Mbps.
Just as USB 2.0 is going to take pole position on the race track and raise the speed bar, FireWire is expected to hit back by coming out with a new version that will transmit data even faster at well over 800Mbps. Technically, the speed is enough to transfer the contents of an entire CD in just a few seconds.
As far as the user is concerned, USB and FireWire are about equivalent as far as usability and simplicity is concerned, unless digital video compression is desired, where FireWire is superior.  As far as popularity is concerned, USB has a much larger share of the market, and is therefore much more prevalent.  Not to mention, essential computer components such as the mouse, keyboard and printer use USB technology, with digital cameras getting a lot of use recently.