So back in October I coughed up the dough and called our good friends at the Tire Rack to get our (still new) X5 some winter wheels and tires. The alloys are non-descript (Type 5 or Type S - I can't remember) but the tires are OE sized Dunlop M2 performance winter tires.
Over the weekend we got about 19" of snow, and I didn't get a chance to do any shoveling until about 11pm Sunday night. The roads around here were still coated in snow, and the wife and kids were asleep, so I thought - hey, why not try these puppies out.
To make a long story short, I could not get this X to slide, I couldn't get it to fishtail, I only got DSC to activate twice (and I was attempting some Rally-style turns) and I had absolute confidence in the car.

If anyone EVER has any questions about our X's abilities in the snow, lemme know. With great tires, all-wheel drive, ABS and traction control - only stupidity will not allow you to drive in inclement weather. These cars can get through anything when properly outfitted.
Now... if I could only get my wife (the regular driver of the car) to actually drive in snow...
Oh well, we drive to Pittsburgh (crooked xoutpost.com sticker and all - that's another story) this weekend. Maybe we'll get white-out conditions on the PA Turnpike!!! YEAH!!!