Really depends on whether you ski/board. If you're going to go up much, get some snowflake-rated tires. I usually get what's on sale. Hankook, Blizzak, Goodyear all make good winter tires.
I bought an extra set of '06 rims that my snows are mounted on. This year, I had them on November-April.
Sure nice to have those summer tires on, however. So much more responsive to drive.