Okay, After getting rather annoyed at losing constantly at chess. I thought of a solution to save me going through on easy to do it.

First Find any chess computer game and play against it on hardest difficulty. Make sure you play second. So the hard computer will then play the first move.
You will then play that move on the harry potter chess challenge. Wait for the harry potter champion to play back and you make that move on the chess game. You will repeat so basically a really hard computer is playing the game.
Once I did it, the computer easily beat the harry potter chess champion.

I recommend using Chess on the vista operating system. But any game should do as long as it has a really high difficulty.

Also I managed to unlock the hard achievement. I completed the game but no unlock. I had auto-saved turned on all through the game. Once completed, I saved my game. Went to option turned auto save off, Saved my game, and achievement unlock.

Dunno if these solutions work for you guys, But there you go my idea's from into the bowl.

if you like to spread the word around other forums all i ask is you mention me in the post.

thank you