¿Como hacer redireccion 301 en .htacces?

En la web que tengo actualmente, se puede entrar:

miweb.com
o www.miweb.com

y como solo quiero que se entre www.miweb.com quiero hacer una redireccion 301 desde .htacces

Actualmente el contenido de mi .htacces es:

##
# @version $Id: htaccess.txt 14401 2010-01-26 14:10:00Z louis $
# @package Joomla
# @copyright Copyright (C) 2005 - 2010 Open Source Matters. All rights reserved.
# @license [url]http://www.gnu.org/copyleft/gpl.html[/url] GNU/GPL
# Joomla! is Free Software
##

#####################################################
#  READ THIS COMPLETELY IF YOU CHOOSE TO USE THIS FILE
#
# The line just below this section: 'Options +FollowSymLinks' may cause problems
# with some server configurations.  It is required for use of mod_rewrite, but may already
# be set by your server administrator in a way that dissallows changing it in
# your .htaccess file.  If using it causes your server to error out, comment it out (add # to
# beginning of line), reload your site in your browser and test your sef url's.  If they work,
# it has been set by your server administrator and you do not need it set here.
#
#####################################################

##  Can be commented out if causes errors, see notes above.
Options +FollowSymLinks

#
#  mod_rewrite in use

RewriteEngine On

########## Begin - Rewrite rules to block out some common exploits
## If you experience problems on your site block out the operations listed below
## This attempts to block the most common type of exploit `attempts` to Joomla!
#
## Deny access to extension xml files (uncomment out to activate)
#<Files ~ "\.xml$">
#Order allow,deny
#Deny from all
#Satisfy all
#</Files>
## End of deny access to extension xml files
RewriteCond %{QUERY_STRING} mosConfig_[a-zA-Z_]{1,21}(=|\%3D) [OR]
# Block out any script trying to base64_encode crap to send via URL
RewriteCond %{QUERY_STRING} base64_encode.*\(.*\) [OR]
# Block out any script that includes a <script> tag in URL
RewriteCond %{QUERY_STRING} (\<|%3C).*script.*(\>|%3E) [NC,OR]
# Block out any script trying to set a PHP GLOBALS variable via URL
RewriteCond %{QUERY_STRING} GLOBALS(=|\[|\%[0-9A-Z]{0,2}) [OR]
# Block out any script trying to modify a _REQUEST variable via URL
RewriteCond %{QUERY_STRING} _REQUEST(=|\[|\%[0-9A-Z]{0,2})
# Send all blocked request to homepage with 403 Forbidden error!
RewriteRule ^(.*)$ index.php [F,L]
#
########## End - Rewrite rules to block out some common exploits

#  Uncomment following line if your webserver's URL
#  is not directly related to physical file paths.
#  Update Your Joomla! Directory (just / for root)

# RewriteBase /

########## Begin - Joomla! core SEF Section
#
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteCond %{REQUEST_URI} !^/index.php
RewriteCond %{REQUEST_URI} (/|\.php|\.html|\.htm|\.feed|\.pdf|\.raw|/[^.]*)$  [NC]
RewriteRule (.*) index.php
RewriteRule .* - [E=HTTP_AUTHORIZATION:%{HTTP:Authorization},L]
#
########## End - Joomla! core SEF Section


RewriteCond %{HTTP_HOST} !^www.
RewriteRule ^(.*)$ http://www.%{HTTP_HOST}/$1 [R=301,L]

¿Alguno sabeis que tengo que modificar o añadir?

Muchas gacias y un saludo

Busca en google: redirección canónica htaccess

;)

No es por nada, pero acabo de buscar, y ponia que añadiera estas lineas a mi .htacces; he eliminado las 2 ultimas y he insertado estas

RewriteCond %{HTTP_HOST} !^www.eluniversodelperro.com$ [NC]
RewriteRule ^(.*) http://www.eluniversodelperro.com/$1 [R=301,L]

y me sigue haciendo lo mismo

ya esta solucionado, las lineas que deciais habia que ponerlas al principio del todo,, despues del

RewriteEngine: On

Muchas gracias y un saludo