.GOV security

I was reading a post here about laptops being stolen from the FEDs and It reminded me of something I read awhile back.

I once read that the goverment's most important data is stored inside PCs that are dissconnected to the internet so that it would make it harder for peaple to nab the info, sorry if I could find the URL I'd post it but anyways the point im trying to get across here is if this info is so important then is NASA, the Pentagon, Nato and other .GOV branch's sites and systems not important to them?

P.S. Im haveing trouble posting wiout getting a 404

P.S. Im haveing trouble posting without getting a 404