Download:http://www.ubuntu.com/getubuntu/download [5]
Features: http://www.ubuntu.com/products/whatisubuntu/904features/ [6]
Upgrading: http://www.ubuntu.com/getubuntu/upgrading [7]
Links:
[1] http://pulse.veltsos.com/category/it/software/foss
[2] http://pulse.veltsos.com/category/it/it-general
[3] http://pulse.veltsos.com/category/it/software/software/os/linux
[4] http://linux.philosweb.com/drupal5/files/image_2_89.png
[5] http://www.ubuntu.com/getubuntu/download
[6] http://www.ubuntu.com/products/whatisubuntu/904features/
[7] http://www.ubuntu.com/getubuntu/upgrading
[8] http://linux.philosweb.com/drupal5/files/image_6_14.png
[9] http://linux.philosweb.com/drupal5/files/image_8_10.png