Not all, just a good chunk for the initial, and being there at the right time.
MS came out with its first version of Windows in 1985.
If you want to call that competition, go right ahead. It was only a sad attempt to copy Apple. Really sad. I tried it. DOS was better. Come to think of it, DOS was better than Windows 286 too.
And you think that that decision was luck?
What was luck was IBM not demanding an exclusive license, as what IBM wanted back then, IBM got.
It's only a matter of time before it brings that capability down to the desktop.
Then why not do it for Vista?
I know that's bad news to you, given how much you've staked on OS X.
You might be surprised to know that the OS I use the majority of the time is W2K3.
I wish Apple well in its competition against Linux. I truly do. But that's all that it's competing against on the desktop.
Since almost nobody is using Linux on the desktop, the recent surge in Apple desktop sales had to be going against something -- Windows.