- dpkg -l
- well there will be A LOT of NOT installed packages.. why would you want to do that? btw, the command
apt-cache pkgnames
will provide you the list of ALL available packages in the repository added in your sources.list configuration - apt-get remove will remove the installed package, but you'll normally keep the configurations, which is the desired behaviour usually.
further info: http://www.cyberciti.biz/howto/question/linux/dpkg-cheat-sheet.php