How to obtain a listing of packages installed that may be used to clone config

["hogan" <hogan@netspace.net.au>]

I've seen some vague reference to this before. But can't figure out when or
where.

A friend is going to switch from Debian to Win2K (I know - completely evil)
for their cable modem sharing machine. I set up the Debian box and would like
to take a snapshot of the config.. They're happy to get rid of old 486 that's
currently doing it as they realise a 486 won't hack it for Win2K, but they
want to put existing HDD (and hence blow away config) into Win2K machine.

Would like to know how to obtain a listing of installed packages on the system
in a format such that I may easily feed this listing to a new install to have
exactly the same packages.

I assume in addition to this package listing, I'd need to take a copy of
existing /etc dir (ignoring parts that are OK in package supplied format)

TIA
ADFH