How to get security updates, but not other packages?

["J. Grant" <jg@jguk.org>]

[Please include my email address in any replies]

Hi,

Presently using debian sarge, I would like to update my system with only
security fixes which have been made available since Sarge was released.
Now sure how to do this.

would "apt-get upgrade" also update non-security fixed packages?

I have this in my sources.lst

deb http://security.debian.org/ stable/updates main

Not sure what the difference is between "apt-get upgrade" and "apt-get
dist-upgrade"

I've read the FAQ: http://www.debian.org/security/faq and the Securing
Debian guide, they appear to omit the info I am looking for:

http://www.debian.org/doc/manuals/securing-debian-howto/index.en.html

It says about just doing "apt-get upgrade" like I was thinking I needed
to.  But does that include uncessary stable package changes?  Or now
Sarge is released are the only package changes for security fixes?

Also, I wonder if this will break anything else, for instance I had to
install the nvidia package from unstable non-free.

Thanks in advance for any tips.

Kind regards
JG