First check which version of R is supported for your Ubuntu: http://packages.ubuntu.com/search?keywords=r-recommended
From the package list it looks like you are using Ubuntu 10.04 LTS (Lucid Lynx), so you may want to upgrade to:
- The current long term support (LTS) release: Ubuntu 12.04 LTS (Precise Pangolin)
- The current release: Ubuntu 13.10 (Saucy Salamander)
Or wait for the next LTS to become available, Ubuntu 14.04 (Trusty Tahr), in April 2014. The Ubuntu LTS releases are supported for five years (https://wiki.ubuntu.com/LTS), so you will want to upgrade soon in any case so you might want to get that out of the way.