There is an interesting article I found on wikipedia.
http://en.wikipedia.org/wiki/Starfish_Prime
Apparently there were some minor EMP effects felt on Oahu, but they were nowhere as serious as implied by this writer who would want you to beleive that there were major power outages. That never happened.
Yes, and that was a 1.5 megaton fusion bomb. AQ, Iran and NK are all still working on fission bombs and years away from serious fusion weapons.
Still, it's worth hardening infrastructure, mounting a missile defense and prosecuting the war vigorously (the latter two for other reasons as well).