These two platforms have distinct advantages and disadvantages against each other and the winner will likely be the solution that walks away with the greatest number of advantages and the least number of disadvantages.
Lets set the stage to see why both sides suddenly see Microsoft as extremely vulnerable, and why it may not be as vulnerable as it seems. (Realize perception rules and is driving this change).
Windows (Sniff), I Used to Love You...
What if Microsoft Ignored Linux?
Microsoft: Vista Is Just the Beginning
Choosing Vendors: The Linux vs. Microsoft Red Herring|
Problems with Microsoft in General and Vista in Particular
For some time Microsoft has been showing signs that things arent going well. Vista was late, and they had to delay it even more to ensure that Dell was not unfairly advantaged. From Dells perspective, Dell was penalized because they had a model that was more efficient than its competitors and they believe that Microsoft contributed, with intent, to them missing their quarter and having to both fire their CEO and bring the founder back from retirement.
To suggest that Michael Dell is upset with Microsoft would be to vastly understate the situation. Livid would probably be more accurate. And as we rolled to the launch, Dell in particular was becoming more and more upset that Microsoft was not listening to them and certainly not being responsive to their needs.
When Vista arrived it was incomplete. Key parts remain missing, the promised marketing plan doesnt appear to be effective, and sales are not meeting the requirements of the OEMs who were depending on it to significantly drive up hardware sales. Microsoft lengthened the period of time that Windows XP would be supported, against the OEMs wishes.
At CES, after working very hard to get systems ready for Bill Gates keynote, the OEMs saw Microsofts Xbox 360 take center stage and get positioned as a media center PC-like product and a competitor for their own offerings. Microsoft has not allowed the OEMs to use PCs as Media Extenders and Xbox 360 game players so they can compete.
As a result, Dell, and other OEMs, now view Microsoft as a problem, and increasingly a competitor they have to deal with, and each is trying to come up with a way to do that individually. At some point I do expect them to organize and address this issue in some kind group fashion. Until then they appear to be trying to help create a competitor to Windows, and since Apple wont license, Linux, ready or not, is the next in line.