What if the H-1B extension was denied

I have a question for expert.

My H-1B will reach 6th cap at the end of Jan, 2009. My PERM was filed 345 days before H1B max out day. So I travelled overseas for 20 days in order to recapture those days. My company has filed the extension. My question is by the end of Jan 2009, my extension is still not approved, and later it is denied, will I be out of status? If I receive the denial after Jan 31, will I still be able to file for H4?

Thank you.