If you want apt to remove the config files as well when you uninstall a program (or maybe as I have removed them manually and is unable to reinstall using apt-get install)

$apt-get –purge remove pkg-name

This is a command i had to learn the hard way as I (accidenly) removed the /etc/munin (a server monitor tool) directory. After I had done this I was unable to get apt-get install to make any new config files in the /etc/ directory. Turns out that removing without using –purge (normaly) leaves the old config files (if I wish to re install later I assume).