How can you transfer Gamer Points between Hardrive and Xboxlive?

I have 4000+ Gamer points on my Xbox360 dashboard and i want to use them to purchase a game from Xboxlive. How can i do this?|||i dont really remember but its through a cable that u can buy at a xbox shop|||I bought a brand new Elite like 2 years ago, and someone offered to buy my points that came with it. He said he could see the points on my dashboard, but I can't even see them!





How the fart does that work?





Edit: I think we may have a mis-communication here. You're talking about your Gamerscore aren't you? That isn't redeemable for games and DLC. It just show how much of a nerd you are.