How about including a basic description of each distro along with links to their download and help sections in an immutable sticky entitled "What is?"?
E.g.
http://www.linuxquestions.org/questions/mandriva-30/
What is?
Mandriva Linux, formerly Mandrake Linux, is an RPM distribution of Linux Operating System first created by Gael Duval in 1998.
While home office is located in France and is developed primarily in English and French, Mandriva Linux is available in most languages.
Home page:
http://www2.mandriva.com/
Wiki(help articles and more):
http://wiki.mandriva.com/
Downloads:
http://www2.mandriva.com/downloads/
Mandriva Store:
http://store.mandriva.com/int/
...