I'm sure Walmart would love a government a contract to supply the military with pre-installed linux laptops. They all would get a certain set of programs, depending on their standardized needs. They would have a central server, (like Lindows used), to provide updates and new programs if authorized. Login via https, enter your passwords, and get a tgz package. They could even have a Perl script to auto-install the tgz. Military computers shouldn't be open to their users installing anything they want, so the red herring of all those linux programs available confusing soldiers, is moot. They don't install or upgrade unless ordered to, and then only from the special server.
Let me ask you..... if you had your own military, would you tell them to use Windows? You probably would choose a specially designed distro, based on Security Enhanced Linux The desktop would be a very simple menu system, with standard icons for map reading/writing, photo/video shooting, connections to radar display, howto's for various weapons, and 1 click ammo ordering. :-)
But, there is also the problem of the intelligence of the military, so linux may not benefit them in terms of security...... the general would probably proclaim that all root passwords be set to the name of his dog, to ensure that all laptops be accessible by any soldier. But even if that occurred, at least there would be no viruses spreading.