On each tradition its a listing of the different schools of magic, aswell as a associated spirit type, obviously this has something to do with the services you can ask a spirit to perform, however im not entirely clear on how this work..
as an example, would a hermetic mage only be able to ask fire spirits to perform combat services for him?

They're not "schools of magic" they are spell categories. Any magician can order a spirit of whatever type they can summon to do practically anything, but when it comes to Magical Services (p.178), the magician has to use a spirit associated with the spell category given in their tradition. So a hermetic mage could ask a Fire Spirit to Aid Sorcery for a combat spell, but a shaman could not.

Ah, thanks.. It all makes sense now, Sorry about the mix up. "Schools of magic" must be a leftover from my D&D time

"Schools" of magic?

So...there's more than just "Evocation"?

yea, actually Evocation is one of the less powerful schools, Basically cause everything that can be done with evocation can be done better with illusions

ahh cool, I'm glad you asked this. It was something I hadn't realized and wouldn't have thought to ask. I'm in the middle of trying to nail down the rules as best I can before I start my new SR4 game.

I disbelieve that.

Wild Magic trumps all!!