I thoroughly recommend Fedora 13 for being a fine intermediate distro.
Fedora 13 Download
http://fedoraproject.org/get-fedora
Fedora 13 Installation Guide
http://docs.fedoraproject.org/en-US/Fedora/13/html/Installation_Guide/
Fedora 13 User Guide
http://docs.fedoraproject.org/en-US/Fedora/13/html/User_Guide/
You download the ISO. image of Fedora 13 then you need to create a Bootable LiveCD for installation
Fedora 13 can also be run direct from the LiveCD from Booting up without touching your Hard Drive
Also worth considering :
Fedora Remix (Fedora with elements of Linux Mint)
http://fcoremix.wordpress.com/2010/05/25/lucky-13/
http://iso.linux.hr/community-fedora-remix/
Again Fedora Remix can be run direct from the LiveDVD without touching your Hard Drive
Also you can try out as many different Linux distros. as you like on LiveCD until you find the one thats right for you DISTROWATCH.COM gives full listings (second lists the major distributions)
http://distrowatch.com/
Major Linux Distributions
http://distrowatch.com/dwres.php?resource=major
LUg.