Hi. I'm guessing you somehow piped the output of wget to the file. The actual contents of the file should be:
Originally Posted by thevoodooproject
You can open the file in gEdit:
## Medibuntu - Ubuntu 6.06 LTS "dapper drake"
## Please report any bug on https://bugs.launchpad.net/medibuntu/
deb http://packages.medibuntu.org/ dapper free non-free
#deb-src http://packages.medibuntu.org/ dapper free non-free
erase what's there now and paste the correct contents. Save the file, close the text editor, and run this:
gksudo gedit /etc/apt/sources.list.d/medibuntu.list
to refresh the repository information; afterwards you should be able to use Synaptic.
sudo aptitude update