Rediretc dynamic pages in wordpress?

I have a wordpress blog http://agurkposten.no that uses page urls like http://agurkposten.no/?p=1865 and so on for posts. There is about 500 posts already and I want to start to use permalinks parameter /%postname%/ witch will make the urls domain.no/title-of-post. The problem is that I have many inlinks to the post pages. How can I rewrite those old urls 301 and keep the inlinks?

 

Just found out that by inserting /%postname%/ the posts are redirected automatically.