Whoops, I missed that evo2 said the same thing.
Linux Mint 10 Julia reached end of life in April 2012
and is no longer supported. You will not be able to get software nor security updates through the Mint repositiories.
It's probably a good idea to install a supported version of Mint. The current release, v. 17, is a long-term release that will be supported until April 2019.