RE: Case for AWD
The differential in your final drive wants to turn the wheel with the least resistance (unless you have some sort of Sure-Grip). So when you're sitting helplessly spinning one wheel, the brake on that wheel locks, forcing the one with more grip to spin. The idea being that this process will aternate from wheel to wheel until you claw you way out of whatever mess you've gotten yourself into.
I've had the front- vs. rear-wheel-drive discussion with my dad before and he says he drove for decades with rear wheel drive without any problems. (He also almost put bias ply tires back on his '65 442 when he restored it...)
What I've found in my short years of experience is what matters more than the wheels you're powering is the quality of your tires. My first car was a '65 Chrysler New Yorker, with a 413 and 2.73 Sure Grip rear. With a good set of all-season radials there wasn't much anywhere I couldn't go in snow.
When I got married I ended up driving my wife's Omni. When I couldn't take the handling of the 165-80 13s, I threw on a set of 15" Shelby wheels with Dunlop GT Qualifiers (the cheapest 205-50 15s I could get my grubby paws on). Those things were scary in the wet, and an absolute nightmare in snow.
So, the lesson -- do your research on your TIRES!