gnus sources.list: ambivalent results for security updates

[brownh@hartford-hwp.com (Haines Brown)]

I have a system which has the following in /etc/apt/sources.list:

deb http://security.debian.org/ sarge/updates main contrib non-free

It works fine.

However, am I correct to assume that the "contrib" and "non-free"
directories are superfluous in this case and can or ought to be
removed?  

I mount and chroot to another disk. When I do # aptitude update from
the chroot prompt, things go well except for the security
packages. I get the can't stat error even though the line in that
disk's sources.list is exactly the same.

A complicating factor is that the disk to which I chroot has a
2.6.8-2-686 kernel, while the booted system has a 2.4.27-2-386
kernel. Is this difference relevant? 

-- 
 
       Haines Brown
       KB1GRM