Change in employment while waiting for I-140 approval - Urgent please comment !!!

[tuffdude]

My GC was started before end of the 5th year of H1b and I-140 was filed in Oct2010. I am still waiting for it to get approved and now am in the 7th year of stay on H1. Right now i have my H1 extended for 1 year based on pending 140. My questions :

- Can i change jobs at his juncture while my 140 is in process ?

- If yes, will my PD be voided or will i be able to file fresh GC petition with the new employer using current Labor Priority Date? Also in this case how will my current H1B be extended ?