I personlly think they get it from the original office in United Kindom. U.S. Jim U.K. Tim. U.S. Michael Scott U.K. David Brent both regional managers last names can be first names or the wirters just think of it and it might just be similiar from the U.K. Office

yeah, i agree, a lot of the names are very close to the uk office.

Actually Jim Halpert was named after a childhood friend of Greg Daniels.

If you watch the convention Q&A Greg Daniels said that he made the American names similar to the UK like Jim/Tim and Kevin/Keith. And that he actually made all the new characters just the same as their real names like Creed, Angela, Oscar, Phylis.

Oscar, Creed, Angela, and Phyllis are obvious. All they did was change their real last names. Jim Halpert and Andrew Bernard were childhood friends with Greg Daniels...the others, don't know.

I think he decided on Jim as the first name after Tim and then Halpert for his friend.