Like all of the great tech rivalries of our time–Apple vs. Microsoft, PDA vs. smartphone, Linux vs. everyone–the battle between USB and Firewire has no shortage of passionate fans on either side.

It’s no coincidence, though, that the majority of Firewire fans are also die-hard Apple fans: Apple has included Firewire 400 ports on all of its machines since the second generation iBook in 2000 and has long championed the interface’s advantages over USB. Even at it’s peak, however, Firewire never captured more than 33 percent of the total PC market share, despite the fact that it had two key features that USB did not, support for both multiple hosts per bus and peer-to-peer device communication. Meanwhile, USB and it’s successor, USB 2.0, are included on just about every PC under the sun.

There’s more bad news for Firewire fans: According to a recent study from In-Stat, Firewire support is decreasing, even in markets where Firewire has traditionally been strong. In the digital camcorder market, for example, 77 percent of the devices shipped last year supported Firewire, down from 85 percent in 2005. While In-Stat believes devices like camcorders and digital camcorders will continue to support Firewire, growth will be non-existent through the end of the decade.

For more on Firewire’s decline:
– see this Ars Technica article