Do you have a source on that? It didn't gut check with me and some quick googling turned up some contradictory, but not decisive, information otherwise [1]
Fourth post on the page gives a source:
This is from Molecular Biology of the Cell (4th Edition) 2004. Alberts et al. Textbook.
"Each human cell contains approximately 2 meters of DNA if stretched end-to-end"
Perhaps a human cell contains several DNA molecules?
1. http://wiki.answers.com/Q/What_is_the_size_of_a_DNA_molecule