Ubuntu 10.04 (Lucid Lynx) was released on 29 April 2010. One of the major differences with earlier versions was the improvement in graphics. Now you don’t need to install the complete OS to copy the wallpapers. You can use the link provided to download the zip file with all files and extract with 7zip. Download .tar.gz archive for complete set of files.
Also, Get Ubuntu Desktop Edition from http://www.ubuntu.com/desktop/get-ubuntu/download and install it.