Being the best striker in World Cup history is no mean feat for someone who was pretty much finished in his prime as you put it. He also scored 100+ goals after being bombed out of Madrid, not a bad tally either for someone pretty much finished in his prime.
The best striker I have seen, above the likes of Van Basten and Romario, Gerd Muller might have come close, but he was before my time.
As for the hattrick against Utd, here it is:
http://www.youtube.com/watch?v=xCayNnIEH88
EDIT: Oh and he will always be Ronaldo for me, the other one can add portuguese or whatever to his name, this is Ronaldo.