Apple Computer, Inc.
The oldest surviving personal computer company (founded in 1976!) it has found itself badly outnumbered by the Zerg (Windows) forces in recent years. Its followers are like religious disciples, the iZealots, and they will always talk about how their technology is far superior to everyone else's, ignoring how much longer it takes to develop and build, and how expensive its units are compared to other civilizations.
Its leader, Steve Jobs, was once cast out of the Apple Collective and became the leader of a splinter group, the Dark NeXT Templars, only to be called back when Apple was in their hour of need. The Dark Templars had formed an alliance with the Humans (UNIX) and taken some of their technology. Their latest superweapon, OSX, uses Human technology in a desparate attempt to save themselves from the relentless onslaught of the Zerg.
Using Apple technology requires heavy reliance on the magical "RDF" fields used by the Templars to zap other user's brains with Psionic Storms. These take the form of things like discussions about "elegance", "ease-of-use", "iApps", and "Photoshop Bakeoffs". Mention anything about CPU speeds or marketshare, and the iZealots will be fully defended using their Shield technology, which can be regenerated by visiting generators at their home base, such as MacWorld Expos.
Despite the ancient quality of Apple hardware, and the difficulty of winning against the rapidly-multiplying Zerg and the annoying, fragmented Humans, they are still the most fun to play with.
Cantankerous, angry, and downright nasty-- that's what describes the Linux operating system and its fragmented bands of determined fans.
Without a proper leader, the Linuxians have often squabbled with each other, split off into warring factions, and generally made nuisances of themselves.
Using this race effectively is extremely difficult and finnicky, but combining units together and using hit and run techniques (like moving their buildings around) gives the Linux civilization extreme flexibility. Linux people like nothing better than to drop nuclear bombs on enemy headquarters, such as the "Halloween Documents".
An ancient race themselves (dating from nearly the time of the creation of Apple from the mysterious Xeroxians) the Microsoft Collective have always been about one thing and one thing only: Winning.
With their leader, Bill "Kerrigan" Gates strongly at the helm, they rarely lose. Much of their success has come from simply churning out more units than anyone else, but clever manipulation of Apple and the absorption of some UNIX technology has allowed them to keep pace technologically as well.
The Microsofties are not purists. They will assimilate any new technology that they think will give them an advantage. Mostly, though, their total domination comes about because of their ability to clone themselves so quickly, establishing new bases all over the map.