epj3 couldn't be more right...the tough part is to get moving.
I don't think you are doing anything wrong with a 330i over a 330xi at all. I strongly recommend snow tires for the winters, as you brought it up...with snow tires you should be fine for the winter. Even if you don't plan on driving your car in the snow, a good set of snow tires for the winter is still a good idea, for several reasons.
First off, if you get the 330i with Sport Package, the stock tires are performance summer tires. In temperatures below 40 degrees, summer tires do not warmup, and therefore do not provide the proper traction. My vehicle came with Michelin Pilot Sport's (18") and I have a backup vehicle to use during the winter when it snows, so I decided not to bother with snow tires, but it proved to be a big mistake. For a few weeks here in NJ, we were getting 0 to 10 degree (F) temperatures at night and at these temperatures, I was able to spin my rear wheels on completely dry road when launch at a mere 2,000rpm. I also noticed that I could not take turns nearly as hard as I could during the warmer months...it literally was like I was driving a lesser vehicle (in terms of performance). Nowadays, "performance" snow tires such as Bridgestone Blizzak LM-22's, Dunlop WinterSport M2's/M3's, and others are becoming really popular. They provide great traction in the snow while still providing better dry-road traction than summer tires in cold winter weather! Another issue with using summer tires during the winter is if you are driving your car and it just suddenly starts snowing, unexpectedly. Summer tires are AWFUL in the snow...the tires simply do not even try to grip the snow and it just becomes a hazard for you to drive your car in the snow. I once got stuck in a parking lot a couple days after it snowed...it was flat packed snow and everybody parked there...so I decided to park (since there was no other parking available) and when I came back to my car to leave, my rear tires were just spinning as if there were in the air...terrible, terrible experience! Whenever I had to drive on snow, such as a couple days after it snowed, and the snow wasn't cleaned in particular places, I felt like the puck on an ice hockey rink.
Sorry if this was long and overwhelming...it's just that I have gone this whole winter with summer tires because I was too cheap to invest in a set of snow tires (I have a backup SUV available to me whenever I needed it), and it still was a bad idea to try to get through this winter with the stock summer tires.