My site used to be on wordpress.com with a non-www domain. Now, after moving to wordpress.org, I have this www in front, and I am trying to do a 301 redirect as in http://forum.bytesforall.com/showthread.php?t=1052, but it doesn't work.

This is how the .htaccess file looks like today:
--------------------
# Use PHP5 as default
AddHandler application/x-httpd-php5 .php

# BEGIN WordPress
<IfModule mod_rewrite.c>
RewriteEngine On
RewriteBase /
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule . /index.php [L]
</IfModule>

# END WordPress
----------------------

How is it supposed to look like after I have added the www to non-www redirect?

Hmm, this is the code I use in my .htaccess file to redirect:

## Redirect www to no-www:
 RewriteEngine On
 RewriteCond %{HTTP_HOST} ^www\.(.+)$ [NC]
 RewriteRule ^(.*)$ http://%1/$1 [R=301,L,NE]

I'm by no means an expert, but this works for me--you might give it a shot.

Thanks, but I'm kind of afraid to mess up the WordPress thingie that is there now. I have no idea what it actually does. I don't want to change anything before I'm certain of what I'm doing.

EDIT

I followed the instructions here: http://www.webweaver.nu/html-tips/web-redirection.shtml
making my htacces file like this
----------------
Options +FollowSymLinks
RewriteEngine on
RewriteCond %{HTTP_HOST} .
RewriteCond %{HTTP_HOST} !^example\.com
RewriteRule (.*) http://example.com/$1 [R=301,L]
----------------
Replacing the 'example' with my domain name, but all it does is making the browser go into a loop. I can make it redirect to any domain I want by replacing the 'example' with other domains, I simply cannot redirect it to myself.

Not solved, but given up. I just let it be the way it is.