We've exactly the same problem.
A neighbours cat comes round every day to mooch some moggy biscuits from us:
He's called Toffee, but we call him Fatman. His humans are out all day, so we do give him the odd tidbit.
Our cat can't stand the sight of him through the window, but when she does go out and comes face-to-face with him, she ignores him and eats grass.
Here she is (my dad decided to call her Winky....):
Best shot of her:
Mike.
