What is the procedure of getting my H1B transferred from Company A to B?

Company A applied for my H1B before April 2013.My name came in the lottery and I cleared first petition also.However right now,my company is not having any projects in US so my H1B has not got stamped.I also got a lucrative job offer from Company B.So My question is" Is it possible to shift to Company B without losing my H1B ?? How can Company B make use of my lottery results ?How can I get my visa stamping done through Company B? What are the chances? A helpful and honest reply is highly appreciated.