Ok, where to start??

Gender in and of itself is not a disorder. Just because a male wants to wear female clothes or vice-versa really has no bearing on a persons gender.

Gender Identity Disorder or Gender Disphoria or Transsexualism is a different phenomena. For a person who happens to be Transsexual/GD/GID, the clothes are very much a secondary thing. What it is about is identity, you know, who am i? what am i? That sort of thing, and for transsexuals that means that they are the opposite gender to what there bodies are.

A good but simplified way of looking at this is:
Sex: The biological sex of a person
Gender: I am a man, I am a woman
Sexuality: i am hetero/homo/bisexual

Contrary to what some feminists have said, gender is something a person's born with and not something that is indoctrinated. I should know, i am transsexual!!
Rain