A simple way to check the Ubuntu version is to look at
/etc/lsb-release file. Run the following command from a terminal windows:
$ cat /etc/lsb-release DISTRIB_ID=Ubuntu DISTRIB_RELEASE=7.04 DISTRIB_CODENAME=feisty DISTRIB_DESCRIPTION="Ubuntu 7.04"
This is true also for other Linux distribution which follow LSB standard, look at About.com for more information.