http://www.justice.gov/criminal/cybercrime/docs/ccmanual.pdf
(I was going to quote some parts of this, but there are too many... giant wall of text.)
Edit: This is also useful: http://www.fas.org/sgp/crs/misc/97-1025.pdf
And I'll quote this part (which is from a case cited in the footnotes):
A computer that accesses the Internet is a computer used in interstate or foreign commerce.
So there's your answer
http://www.justice.gov/criminal/cybercrime/docs/ccmanual.pdf
(I was going to quote some parts of this, but there are too many... giant wall of text.)
Edit: This is also useful: http://www.fas.org/sgp/crs/misc/97-1025.pdf
And I'll quote this part (which is from a case cited in the footnotes):
A computer that accesses the Internet is a computer used in interstate or foreign commerce.
So there's your answer