If a girl is wearing a tight fitting pair of jeans, or a skirt that reveals her legs, then yes, I will pay attention to her legs, but no more than any other area of her body. I understand your concerns, but from your profile picture, you appear to have nothing to worry about! :)
Legs can be sexy but I personally don't focus on them much. Some guys love legs (like boobs or butt) but it depends on the guy. And we aren't as picky as you women are (ie, they don't have to be "perfect" legs).