Slackware Linux 13.1
The latest stable release, 13.1, came out at the end of May - I'm a bit ashamed to say that it has taken me this long to get around to installing it. It is (of course) available in 32- and 64-bit versions, on an ISO DVD or 6 ISO CDs.
The Slackware installer will appear "primitive" to those who are accustomed to the spiffy GUI installers that most of the popular distributions use. This is not a distribution for beginners, and if the text/curses based installed puts you off, or intimidates you, then you should probably stop immediately and try a different distribution. In fact the procedure itself is clear and easy to follow, and in the simplest cases will consist of not much more than pressing Return to accept the default choices. There are more choices and options than most other distributions offer, particularly in giving you extensive control over which packages are installed and which are not.
Assuming that you accept all the defaults, which installs just about "everything", when the installation finishes and you reboot... you might be in for another surprise.