Microsoft is too expensive to buy and both offerings are operating system platforms which dont change the market dynamic, leaving choice three for this example. However, you could argue that IBM and Apple are working on choice two with their thin client and iPhone efforts, and that the iPhone is probably going to be more successful at penetrating the enterprise than Snow Leopard will be. (Well leave that for another time.)
So to embrace and extend Windows, IBM and Apple have two distinctly different problems. For Apple they need to be vastly more open than they are, and IBM needs to ensure there is one simple OS choice and that the product is at least as easy to use and its future is as well understood as Windows.
The problem is that Linux is still too much like UNIX and not enough like Windows to fulfill the embrace/extend requirement. Too many distributions and too little commonality between providers will keep it from moving on this opportunity. To succeed there needs to be one compelling Linux distribution and that wont happen.
Apple has nearly the exact opposite problem. Their offering is a true desktop product, easy to use and highly consistent. But Apple is so closed and proprietary they make Microsoft look like an Open Source company by comparison.
Apple is also a single vendor solution, and one of the major concerns surrounding Windows is that Microsoft has too much power; Apple makes that problem worse because they lock in the hardware as well. To succeed, Apple would have to spin out their platform so that the hardware isnt locked to a single vendor and becomes vastly more open (particularly with regard to roadmap). They wont do that.
In sum, neither IBM nor Apple will go far enough to embrace Windows to truly displace it. IBM cant because it doesnt own Linux, and Apple simply isnt willing to.
The Paris Hilton Angle
As weve seen, John McCain compared Barack Obama to Paris Hilton in an attempt to take the advantage of his celebrity and turn it into a disadvantage. Recall that Steve Jobs, in facing iPod competitors, spoke of both video and Flash as stupid (until he was able to do both) because they provided advantages to his competitors. This suggests McCains team is reading partially from Jobs playbook.
The way that Paris Hilton responded (its actually watching the video) was brilliant.
Instead of complaining, she turned this into a media forum on herself and took the highest profile disagreement between the two parties and made it her own. If you listen to the video you will hear a blend of McCains and Obamas energy policy that is arguably better and more likely to get through congress than either candidates plan.
The big thought here is that what is needed to displace Vista is a blend of the approaches that IBM and Apple are making. A combination of the open aspects of Linux with the simplicity of the MacOS.
To win any contest you have to be willing to do what it takes to win. Neither IBM/Linux nor Apple will do what it takes to win in this space. They can gain share but, in the end, their efforts to truly displace Microsoft will fail.
It is with some humor I point out that Paris Hilton seems to get this better than they do.