No problem, the Prius is a fine cold climate car. My 2004 Prius starts the same in -20 as it does at +70 (though cold weather isn't great for MPG in any vehicle). The Vehicle Stability Control, which was available with the higher option packages in 2004, prevents doughnuts when you are going anything like a reasonable speed for conditions. This option really works well, so look for a Prius with this option.
Traction is similar to any front wheel drive car, so you should have four good snow tires such as Nokian WR-g2 (
http://www.nokiantyres.com/ http://tirefactory.net/ ). These not only have great winter traction, but they have very low rolling resistance as well--better than the original equipment tires.
The Prius has just over five inches of ground clearance, so it's not for deep off-roading (just like any car).
www.nokiantyres.com