Merc,
Hit the gym. Run that treadmill and hit the weights every other day and get yourself lean and mean. (I am assuming that if you say you look like Wayne Knight, you could stand to tone that physique a bit). Why do I say this? Because you will have more social confidence and that includes dealing with the opposite sex. And from what I have read from you in this post, it seems that a little confidence, my friend, is what you need so you can shine.
My advice is partly based on personal experience as well, as I used to be a shy, skinny, nerdy type back in high school. After I started hitting the weights and playing hockey, I just developed more confidence and got better at talking with girls.
I'm not saying all women are shallow and judge men on their looks, but it is part of the whole package, right? You even said that you prefer certain physical characteristics in women, so you should expect others to hold you to a certain standard as well.
But this is not to please certain women, Merc. This is for YOU. You look good, you feel good. Confidence is sexy, man. You know you're a smart guy, so that surely can't be the problem. Your lack of confidence lies elsewhere. And if you are willing to be honest with yourself, I am sure you will know where it is. It may not be physique (if so, I apologize... I don't know much about you except what you have told us in your posts), but wherever it is, take the initiative and solve that problem. Once you eliminate some self-perceived deficiencies, you'll be twice as confident -- and twice as attractive because of that. Remember, much like these alter egos in this forum, any machinations of fear or inferiority come from a real source. Find out what they are and deal with them, Gestappo style.