2002 Dodge Ram Power Steering Leak = Rack and Pinion?

My truck recently developed a leak in my driveway. It is pink and foamy. I dont drive it too much, 53K, and it has been sitting for over a month during some somewhat cold weather 15degrees for about a week. This is when I noticed the leak. I drove it to my mechanic and he says the Rack and Pinion is bad. It drives fine, no noises, but it has pulled to the left since I bought it used in '05. I read complaints about the '02 Dodge where people replace the Rack and it goes out soon thereafter. My question is, how certain would it be the Rack, would this cause the Foam, or could the freezing temps have something to do with this? Next question, I had an old truck once with a noisy leaky rack and I drove it for another 80K before the truck died; so it is crucial that I replace the Rack and Pinion or can it be driven as long as I keep an eye on the fluid. Would this be a danger to drive, can the seals blow out and lose steering. What causes these to go bad? Thanks to all in advance.

You can always steer even if you loose all your power steering fluid, but it will be very difficult. You could just keep an eye on it for awhile.