how enable crossover frequency sw

Hope it's put right in here.
Explanation first:
I own a 'Teufel Concept E Magnum' - 5.1 System, put behind a Soundblaster Audigy 2 and normally i am supposed to set a crossover frequency for the sub in the settings found in Creatives' Speaker controls.
But they aren't (yet?) available under the Vista-drivers and poor me couldn't get a bit of bass out of the sub.
Maybe i just didnt find a way to get this working...so is there anyone with a kind of tip or trick? Is it even possible to use all this EAX-thingies (Media source and so on) under Vista? Just didn't dare to try to install it yet.