I've ran in -40 windchill and been nice and toasty. Here's my opinion on running gear:
If you absolutely MUST have THE BEST TECHNOLOGY, buy Craft and only Craft for tights, tops, and jackets. It is very expensive, but it is head and shoulders above everything else. I highly recommend their running pants. They are windproof in the right places and are articulated at the knees.
Next to Craft, Nike makes some good stuff, especially tops. I like their thermal shirts. Get a thin one and a thick one; wear both. As for jackets, I have a North Face one I got as a gift that I wear now, and it's okay. But I used to have a Pearl Izumi jacket a few years ago that was top-notch. I've worn some New Balance and Mizuno stuff, and it's okay. I prefer to get an ultra-thin jacket and back it up with two thermal shirts, instead of the jackets that try to integrate insulation and windbreaking into one garment. It gives you more flexibility for, say, a snowy 25 degree day or a workout. As for gloves, buy the cheapo thin woven black gloves at target, and also buy a "nice" pair of running gloves/mittens or "lobster mitts" like the nordic skiers wear, and wear the thin ones as a liner, or for warmer days.
Get two hats, at least one of which should be a very snug fitting one which COMPLETELY covers your ears. The other one should be thicker; wear that one on top on colder days. Smartwool makes a good "outer" hat, but you need a tight-fitting one underneath or the wind will lift it up and get your ears cold.
If you are serious about running in very cold weather, get a good facemask too. I've found that I can't really breathe if I don't have a mask with holes over the mouth. I have a "half facemask" that velcros in the back that I really like, but I don't remember the brand. I'll toss it in my jacket pocket if it's colder than 10 degrees or so, and if I think I need it I can toss it on.
I do not really recommend Adidas or brooks, as their stuff is usually too loose fitting. And STAY AWAY from asics, their clothing is just garbage. Cheap fabrics, poor fit. My college team had a deal with asics and all of our stuff sucked.
Oddly enough, the same plain running socks I use in the summer work great in the winter. I almost never get cold feet, except when I wear my Kinvaras....the upper is way too thin!