As I figured Richard Harris' replacement will be Sir Ian McKellen.

McKellen Heads to Hogwarts
British acting knight Sir Ian McKellen will replace the late Richard Harris as Professor Albus Dumbledore in the third Harry Potter movie. The 63-year-old star, who also plays wizard Gandalf in the Lord Of The Rings Trilogy, is set to appear in the third installments of both rival films - after signing to take on the role of the Hogwarts headmaster in Harry Potter And The Prisoner Of Azkaban. McKellen takes over the role from Harris - who died of cancer in October. Movie bosses had hoped to cast Harris in the new film - which is due to begin filming in February - by using computer animation and film footage. But they found they did not have the required film available. Fellow Brit Christopher Lee - another Lord Of The Rings star - was among those tipped to replace Harris. A source on the Warner Bros movie set says, "Everyone has been sworn to secrecy about Ian McKellen getting the role of Dumbledore. One of the production staff let it slip and now it is spreading like wild fire. He got the part just before Christmas but Warner's won't announce it until the New Year. Bosses thought he was the perfect replacement for Harris and, as we all know, he is capable of playing the part of a wizard. They are not worried about people getting The Lord Of The Rings and Harry Potter confused. They are two very different films."

(From IMDb.com)

(Edited to add a question mark to the title.)

Well, I'm sure that Sir Ian will be a wonderful Dumbledore, as he's already been a wonderful Gandalf. I thought, however, that Peter O'Toole was supposed to take over the role of Dumbles, but that's just been a rumor. So now we can already put a face to the name

You're right Pearl, Peter O'Toole would have been good, but I think it all comes down to how much McLellen looks and spounds like Harris. Of all the possible people I could think of Sir Ian was the only one I could think of who could pull it off.

I think I would have chosen Ian too, based on having someone who looks and sounds similar to Richard Harris, simply to make the transition as smooth as possible. It really bugs me when a new actor or actress who looks nothing like the previous one comes in to play a part. It is most noticable on tv shows, but it has happened with movies that have several in the series.

I'm not at all happy with the choice. Don't get me wrong, Ian McKellan is a fine actor, I just think that there were several other fine actors who would have better done the role. Peter O'Toole is one of them Sir Patrick Stewart is the other. I'm biased because McKellan is already playing a wizard in the Lord of the Rings movies, but I think that will take away from his playing Dumbledoor. I'm glad they didn't give the part to Christopher Lee though.

Now the IMDb is changing their story!

The Next Dumbledore?
Michael Gambon, best known in Britain for his Shakespearian roles on stage and for his starring role in the acclaimed 1986 TV miniseries The Singing Detective, has been selected to replace the late Richard Harris in the Harry Potter movies as Dumbledore, according to E! Online , which cited no sources. The website, which is affiliated with the E! Entertainment Channel but maintains a separate editorial staff, noted Wednesday that it was unable to confirm the casting with Warner Bros. because of the New Year's holiday. Gambon's name has been prominently mentioned in the widespread speculation about who would replace Harris in the role.

(IMDb.com)