The 2000 Impalas to current 08 models are all front wheel drive. Even with front wheel drive it is still advisiable to keep some extra weight in the trunk to help keep the back of the car stable during manuvers on slick roads.
Unfortunately front wheel drive. I've only had mine for a week and haven't played in the snow yet. I can tell you it's a blast when you turn off the traction control at a stop light. People don't expect a 4 door sedan to light up the tires.
Yes the ss is good in the snow and it is also better in the heavy rain against hydro plaining. It sticks better than my buick regal on this bad section of highway near my house. Maybe because of the extra weight of the v8 and the wider tires.
Does your have the stability control? If so how does it perform, and do you have to add weight to the trunk? We down here in Denison, TX just got our second snow of the year today (which two in one week is really strange, for we usually get one per winter) and tomorrow morning I will be taking a trip into Dallas and though mine is RWD I always add some weight to the trunk.