The Value of Purity

So, how do I show that there is great value and reward in purity when our culture tells us that we are losers if desire said purity?  What can I say to teens who have all of their sexual "theology" from music, movies, the internet, and books?  (shudder, shudder)

I'm thinking of doing a talk in a couple of weeks on sexual purity.  It's going to be geared towards the teen girls, but I think I'm also going to invite some "college & career" girls if they want to come.  I'm thinking of entitling it: "So you say that you love and follow Jesus and want His best for your life? Well this is kind of what that looks like in the area of sexuality."  Kind of long. Maybe too long.  

I definitely don't want to bring to them a list of rules.  Our purity must stem from our love and passion for the God who made and saved us.  Anything a part from that is legalistic sin. Therefore, I know that I need to be careful about what I present and how I present it.  I want to talk about how important holiness is to God.  I want to talk about how we are supposed to be being made into the image of Jesus (sanctification).  I want to say how important righteousness is.  Like is says in Romans 6, "How can we sin any longer?  We died to sin!".  But then you have to talk about how sex outside of marriage actually is a sin.  Something a lot of these girls don't know.  It's about "whenever the time is right for me"  and  "if I feel like we really love each other".  Commitment people!  Ever heard of that word?  But, no, most of them haven't.  Wow - this is going to be difficult.  But I feel like I'm supposed to do it, so I'll trust that God will lead and guide me.  

Thoughts?