Secure Remote Application and OS Deployment?

[Chip Panarchy <forumanarchy@gmail.com>]

Hello

Been doing a lot of research of late into the installation of Windows
over a network (using the Unattended BootCD and a Network Share). Also
a little into RIS (WDS).

I am interested in how this could be done securely. To summarise what
I would like to know, I have summarised it into the 2 questions below;

1. Is there a Secure way to Remotely install: Windows XP, Windows
Vista, Windows Server 2003, Windows Server 2008, Linux (GNU way, so I
can install the feature on any *nix) & Mac OS X, if so, how?
2. Is there a Secure way to Remotely install applications (from a
central repository) to the aforementioned Operating Systems, if so,
how?

NOTE: If it isn't possible for some of the OSs, please tell me which,
then please continue to answer how it will be possible for the others.

Thanks in advance,

Chip D. Panarchy