Stacey if you want to see some of the protective clothing, including the padded shorts with cocix(?) protector, go to the bbc sport website-skiing, Graham Bell does some equipment videos on there you may find useful.
To start with, i would recommend getting some impact shorts. They take the sting out of falling and are great insulation against the cold.
Secondly, knee pads are not a bad idea, but instead i prefer to wear knee supports (like you get for sprains and twists). They dont get in the way, and are quite effective.