Winter driving a 325xi

I have a new to me 2001 325xi. I am loving the car. But it does behave differently from other cars I have driven in adverse winter driving conditions. I have lived at 7200 feet above sea level on the CO front range since 91 and have lots of experience driving in winter conditions. I have driven numerous FWD, AWD, 4WD vehicles in that time (Jeep Cherokee, Audi Quatro, Subarus, Ford SUVs and pick up, Honda CRV and Accords). The BMW has not failed to get me anywhere, nor been unsafe at any time, but the rear end seems to break loose easily in turns and then the DSC light starts blinking and the car gets back on track, but it feels weird, maybe its just different. I am mostly curious about when to hit that DSC button, I think there are 3 modes available, and when to use it?