You're right,
http://ninjette.org works, but
http://ninjette.org/forums doesn't. (they both still bring up the pages that you'd expect, but the forced www isn't appearing). Here's the code I was using:
Code:
RewriteCond %{HTTP_HOST} ^ninjette.org [NC]
RewriteRule ^(.*)$ http://www.ninjette.org/$1 [L,R=301]
(2 lines for each domain). I'll try it with yours later today, need to get ready for an actual motorcycle ride in a little bit.