Re: Ubuntu 10.04: libxcb-sync0 >= 1.6
Ubuntu 10.04 has reached end-of-life and no more upgrades are available. This will apply not only to PPAs but all the packages.
It's best to upgrade your system. 12.04 is the next long-term support release and will be supported until 2017. If you don't like the idea of running Unity, there are plenty of other options available.
BACKUPS are unsexy — until you discover you should have done one yesterday.
Spare your nerves and do one before you upgrade or install.