You need to delete every instance of hoary from your /etc/apt/sources.list.
Code:
gksudo gedit /etc/apt/sources.list
You will be prompted for your user password.
Delete all Hoary repositories, save the file and close gedit.
Code:
sudo apt-get update
to refresh your sources.list
Alternatively you could go here:
http://www.ubuntulinux.nl/source-o-matic
You can create you own sources.list automagically.