Welcome aboard Sandy!
if you live in a snowy region, i think it's best to get a separate set of rims/ snow tires for the winter. no matter what drive set up you have. snow tires work better that a/s tires in the cold, even if there is no snow.
i live in michigan, and during past 3 winters, i haven't had too much trouble w/ my rwd in snow. traction control kicks in sometimes, but never a fishtail. (ground clearance is the biggest issue i have in the snow, but i don't think it'll be that bad for the 325.) but you'll have to be the judge of that. awd does give you more confidence, and is little bit higher off the ground.