Search just generally sucks in general. I see your thread is in Winter Cycling now, though there's a lot more traffic in the commuting forum.

I've never gotten a flat in the winter. Seems to be less likely to be able to wedge something sharp hard enough between pavement and your tire to puncture it when everything is covered with snow which it can push into. (Spring is the worst, when the snow and ice melt and sharp stuff is left sitting on hard pavement.) I do put flat resistant tires on my winter bike anyways, but I'd personally be hesitant about putting tire liners on. Tire liners have a reputation for occasionally being installed wrong and puncturing the tube themselves by rubbing the edge of the liner into the tube. Just my 2 cents.

Your profile doesn't say where you live. Knobby tires help with snow (they help but certainly don't make it easy). Studded tires grip on ice, where knobby tires don't make much of a difference. I created a thread on winter tires here you might be interested in:
http://www.bikeforums.net/commuting/...fat-bikes.html

If there's any ice, I personally will not ride without studs. It's to dangerous for me, for a problem I could solve for $100-$200. Some people claim that they're "fine", but rubber doesn't grip on ice, and the people I've known to try it always seem to eventually have a bad fall. (Studs still leave snow slippery, but grap onto sheer ice like it's 80% pavement in my opinion).