The -big- secret to driving in bad weather, is 'finesse'. go easy on the gas pedal, easy on the brakes, and easy on the steering. "Plan ahead", and minimize the need for abrupt changes.
A 'limited-slip' differential ("Posi-trac", or similar) is a *big* help in adverse conditions. 4wd is even better (it always includes 'limited-slip' between wheels), but the advantage of 4-wheel over 2-wheel is minor, compared to the benefits of limited-slip over a standard rear-end.
Emergency handling (regardless of whether it is snow, rain, or dry-pavement) characteristics -- and what you do as the driver -- *do* vary greatly, depending on whether you have front-, rear-, or all-wheel drive.
This is _mostly_ a matter of being familiar with what you have, and knowing how to use it. Front-wheel drive has some advantage -- mostly in that it is easier for the _un-skilled_ driver to 'do the right thing'.