The official information that I received from my recruiter is that there are 3 educational qualifications (#3 is what you are interested in). This information is taken from the July 2007 program authorization form.
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1) Baccalaureate Degree from an accredited university
2) No specific degree is required, however degree in computer science, mathematics, engineering, and foreign studies with a language emphasis are preferred.
3) Minimum requirements include an overall GPA of 2.2, one year of calculus with a "C" average and one year of calculus based physics with a "C" average.
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I'm in a similar situation as you. I got a degree in Management Information Systems, which only required that I take Calculus 1. When I found out about these requirements, I enrolled in Calc 2 immediately. Then I took calc-based Physics 1 this summer. I'm now finishing up calc-based Physics 2 this fall. Don't let this requirement stop you. If you want to be an Information Warfare officer, then do everything you can to get there.
So, the short answer is, Yes, you need 2 semesters of both calculus and calculus-based Physics.
I've uploaded the actual official form that this came from.
Also, the Navy will only be taking 18 applicants (via OCS) for Information Warfare in 2009. You must be a competitive candidate in order to have a strong chance to be selected. I am not an IW officer (but I am trying to become one), but I can only imagine that if you don't meet this minimum requirement that it will be that much easier to reject your application.
Good Luck!
Regards