There are lots of different types of linux. Kubuntu, Ubuntu, Red Hat, SUSE, Debian to name a few.
Each one has it merits (And downsides).
You can usually download an ISO of the CD (Not recommended if you have a download limit). So you can also order a CD, but these usually cost a couple of £/$
All the people I know who use Linux as their main workstation use Kubuntu. This has the KDE desktop.
Their website is
http://www.kubuntu.org/
To order a CD of Kubuntu go to
https://shipit.kubuntu.org/