Yep, know that. But I am no fan of Hamilton or McLaren (I refused to buy a MacLaren pushchair for my Daughter when she was born, even though the two companies are not related!) - the only upside to Hamilton winning last year was that Ferrari lost! Although they did win the constructors championship (booo!).
As to other examples (apart from 1958 above) which would've changed the outcome:
Jim Clark in 64 and 67 rather than Surtees and Denny Hulme
Mario Andretti in 77 rather than Niki Lauda
Alan Jones in 79 rather than Jody Scheckter
Alain Prost in 81, 83 and 84 rather than Piquet, Piquet and Lauda
Didier Pironi in 82 rather than Keke Rosberg
Nigel Mansell in 86 and 87 rather than Prost and Piquet
Senna in 89 rather than Prost
Massa in 08 rather than Hamilton.
Thumbups for either Scottish or WilliamsF1 victories! (although admittedly 82 would've lost Williams a championship and 87 was neutral). 2009 is my 30th season of supporting Williams!