Plot holes filled?

[eggplant107 at hotmail.com]

No: HPFGUIDX 16732

It seems to me that Goblet Of Fire has a plot hole, why did Voldemort 
need Harry to win the Tri Wizard Tournament? Why couldn't Moody turn 
a door knob or one of Harry's books into a port key? Surely in the 
course of a year he could get Harry to touch something. Rowling 
should have had Voldemort say something like this to his death eaters 
in the graveyard. 

"There is a powerful spell preventing port keys from working at 
Hogwarts but during the Tri Wizard Tournament people would be 
arriving from all over the world so I knew the spell would have to be 
temporarily removed, if not in the castle itself at least on the 
grounds. It also amused me to have Harry Potter whisked away to his 
doom at the very instant he thinks he's going to attain his greatest 
triumph. And I did it right under Dumbledore's nose with the entire 
world watching, people can now see with their own eyes which one of 
us is more powerful."

Now I just need to just figure out why anybody would want to watch 
the second and third tasks. Staring at a hedge and the unruffled 
surface of a lake lacks a certain visual appeal.