Hi.
After install 14RC there is problem with repositiories. In Muon after check for new packages it said:
http://ppa.launchpad.net/netrunner-os/frontier-14-packages/ubuntu/dists/frontier-14/main/binary-amd64/Packages
404 Not Found
http://ppa.launchpad.net/netrunner-os/frontier-14-packages/ubuntu/dists/frontier-14/main/binary-i386/Packages
404 Not Found
http://ppa.launchpad.net/ubuntu-wine/ppa/ubuntu/dists/frontier-14/main/binary-amd64/Packages
404 Not Found
http://ppa.launchpad.net/ubuntu-wine/ppa/ubuntu/dists/frontier-14/main/binary-i386/Packages
404 Not Found
The file you would need to edit manually is /etc/apt/sources.list. You should also be able to edit these lines using software sources in synaptic or from within Muon.