<IfModule rewrite_module>
RewriteEngine on

RewriteCond %{REQUEST_URI} !^/(skin|js)/

RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteCond %{REQUEST_FILENAME} !-l
#RewriteRule ^(.+)$ /default.php/$1 [L]

RewriteRule .* default.php [L]
</IfModule>

thanks a lot