Originally Posted by atl_hooligan
That's a Smith Machine. I would urge against it's use for squats. It can be very hard on your knees. If you do a squat properly the bar will not travel in a perfect vertical plane...
That's just one opinion. I use the Smith for squats and have had no problems.
Here's another opinion on the subject:
http://www.exrx.net/ExInfo/SmithSquat1.html