Call me a pessimist, but I don't really see how the quality and features of Leopard or (the lack of) them in Vista would really matter the big picture. For Apple doubling market share to 4-5%[1] of the PC market would be a really big thing but it would not really matter to Microsoft, they would still have the huge, constant stream of income from their Windows and Office products and most people would still see just Windows machines in the store they are purchasing their computers.

Sad but true.

[1] estimated unscientifically, I don't have the latest figures but Apple's computer sales were flat during 2002-2004 which means loss of market share, last year they might have gained a bit.