1. L1B Approved on Feb 2nd 2006
2. Started working on L1B from April 1st 2006
3. H1B w/ COS approved October 2008. Then, could not work for H1 employer due to bad economy and no jobs
4. Stuck to my L1 employer. Got L1 Extension Feb 2009 w/ Extension of Stay
5. Got L1B Stamped in India in Dec 2009
6. Leaving L1B employer by the end of this month
7. Now want to work for H1B employer mentioned in Point 3 above.

NOTE: H1 employer did not cancel the H1.

What do I need to do? Can I just move over and start working for my H1 employer? Or do I need to intimate USCIS? Is there a legal process. If so how much time and money would it cost? Can this be done while I start working for H1 employer?