The blizzaks WS50's on my 04GT were so strong, I let my wife take the car to work during a snow storm. People thought she was nuts pulling into an unplowed parking lot in a Mustang GT in the middle of a snow storm. What really freaked em out was the fact that she put the car in reverse and backed up the hill to her corner spot without spinning the tires.
Blizzaks are a bit pricey, I got mine used off of craigslist with rims for 275. Even being seven years old on the front (will be replaced before this winter) and four years old on the back, they still made my Stang perform like a 4x4 in the winter. I feared nothing but high drifts; lets be reasonable. Three inches of unplowed or messy parking lots didn't stop the steed. The car performed flawlessly. I felt safer in the GT than my posi fwd Nissan Sentra that I had previously sold to purchase the GT.
TIRES ARE EVERYTHING.
If you notice the snow on top of the tires of the 4x4 Xterra, it hadn't been moved, I took the Stang out. The Xterra runs the Bridgestone Dueler A/T's Revo's.