H1B extension with new employer

[rahulgarg]

My H1B 6 yrs is expiring in Aug 2011. I have my I-140 approved with my current employer A. I am thinking to join another company B.

Is there any problem If I change the job now. can My new employer B directly file for 3 yrs H1 extension based on approved I-140 with my current employer A. I have heard that H1B extension could be filed only within 6 months of expiration of H1B.

so If I wanna change the job, wud new employer B, be able to get H1B transferred active till Aug 2011 and file for extension later on when it falls within 6 months window or could it directly file for 3 yrs extn now.

In former case, If my current employer A revokes the I 140 before my new employer B could file for 3 yr H1B extn based on this I-140. Could that be the case?

Any help appreciated

Thanks

Rahul