problem: both permalink and old link structure working

Hi,
i’m using the latest wordpress version 3.0.5,furthermore,i’m using permalink pretty link, anyway, my problem is that
1- permalink: which look like http://exemple.com/blog/friendly-url-id.html
2- Old url structure: which look like: http://exemple.com/blog/?p=id

now,both permalink and old url structure are working, in other meaning
all links that looks like http://exemple.com/blog/?p=id don’t redirect to http://exemple.com/blog/friendly-url-id.html which result to duplicated content.

in a nutshell, i want to redirect 301 permanently http://exemple.com/blog/?p=id to http://exemple.com/blog/friendly-url-id.html

i used permalink validator and others plugins, but, unfortunetly, they restrict my blog to show up in google and other seach engines

…of caurse i have .htaccess file:

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

Please help me, i’m in a dielma since several months, and yet i didn’t figure out a solution.

thank you