Winter Cycling - new bike

I just got a new bike and have begun cycling in the belly of the beast - a Northwest winter. It just started snowing, and has iced over slightly today. I bought a 2008 Specialized Globe Centrum Sport (single speed), added fenders and crank brothers Mallet "C" pedals. The guy at my local LBS didn't recommend studded tires, however; I'm running Specialized Pro MTB tires. Maybe you guys might have some insight as to running mtb tires in winter, over textured ice, frosty roads, and snow. I only slipped once - I had fun in the powder, though - and want to hear some insight as to whether mtb tires are the right stuff for snowy and icy unsalted roads. It's been fun, somewhat challenging, and I've never commuted to work before, nor have I owned a single speed (with the exception of my childhood mongoose bike.) I have a padded motorcycle jacket from my motorcycle - would you recommend riding with that in case of slipping? I may look goofy, but I know I'd be okay if I busted...

Do yourself a favour and buy a set of the Nokian Tires. If you do a search on the forums you will see that most people use the Hakkapeliita for commuting on roads with potential ice during the winter. I personally run the W106s 700x35c on my singlespeed during the winter. You can also get the W106s in a 26 x ? There is a also a more aggressive studded tire called the mount and ground but it is for more "serious" winter riding.
Rather than slip and get seriously hurt during the winter get a set of studded tires.

Where do you live? And how can that LBS guy dismiss studded tires?

Southern Oregon, high-desert country. We get a fair amount of snow in the winter in these parts. It gets sunny out during the day, then below freenzing at night. Oftentimes, however, it's pretty dry out. It was 17 this morning. It was a little icy out, but I'm not moving that quick on the roads. More or less taking my time and I haven't been through any deep ruts. There is a lot of texture to what I'm riding on - not like "sheets" of ice. In fact on my 26" MTB tires on icy/snowy roads I didn't slip at all riding in this morning. As for the guy at the bike shop - he indicated that he has never run studs and rides 365 days a year. He has lived in southern/central Oregon his whole life and said just watch out for the black ice. So far so good - I'll keep riding carefully and see how the ride does. if it gets awful slippy I'll get studs - at least for the front.