How could George Lucas take out the original actor who played Anakin aka Vader and put Hayden Christenson in.

It just about ruined my movie viewing experience. It's not enough for me to wear off the movie, but for some reason I have a big problem with changing a classic.

Adding a scene was ok I thought. I wasn't found of it but it was fine.

I also started to think about the actor who played Vader originally, isn't it bad for him?

Well there is nothing you can do about these things.