H1-B Visa stamp requirement after visa transfer?

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Hi, I am on an H1-B visa and I have recently changed jobs. My visa stamp (and approval notice) with the old company was valid till June 2003. Now, after filing for a visa transfer to my new company, I have already received an approval notice, which is valid until 2005. My question - If I am planning to travel abroad in Dec 2002, do I need a new visa stamp from a consulate abroad before I reenter the US ...or can I use the approval notice for the new company (and the visa stamp from the old company) at the immigration/ customs counter for reentering the country? Would appreciate direction from somebody who has been through this - thanks