Live CDs - a way to choose your distro
A Live CD allows you to test-drive the usually latest stable version of KDE SC without the need to install Linux or to change your existing Linux installation. These distributions boot and run completely from the CD and don't modify your hard disks. They can therefore be tried on a Windows computer without risk. All listed CDs are freely available for download.
Mandriva One
The One edition of Mandriva Linux is a Live CD
Kubuntu LiveCD
A live CD version of Kubuntu Linux, Ubuntu's KDE Plasma Desktop brother.
Fedora
A fast paced distro targeting users who want the latest and greatest available in the world of FOSS. Fedora KDE usually has the latest stable version of KDE in the repositories, and beta versions are usually shipped via supported extra repositories.
Mepis
Based on Debian, Kudzu by Red Hat. The disk also offers installation to hard drive.
PCLinuxOS
Based on Mandrake (now known as Mandriva).
Slax - Live CD
Based on Slackware. 8cm CD-R. With modular structure and pseudo read-write CD filesystem.
OpenSUSE Live-CD
It allows to try OpenSUSE with KDE SC and install it to hard drive.
Aptosid - successor to Sidux
Aptosid is an operating system based on the Linux kernel, Debian's branch (called "Sid") and many free and open source applications.
Pardus Live
Pardus is a KDE based Linux distro which offers one of the best KDE integration. You can tryout Pardus Live without installation.
New Live CDs and DVDs are becoming available all the time. If you've heard of a distro and think you'd like to try it, do an Internet search for it. You may well find that a Live CD is available.