The tablet war has barely even begun with Windows 8 still a ways away.
I don't think Windows 8 does much for the tablet war as much as it brings the old tablet PCs more up-to-date, which is still an interesting proposition as I am an owner of HP tablet PC.
However being stuck with the keyboard and Intel CPUs, I just don't see how Windows 8 tablets compete against the paper thin profiles, low heat and long battery life of ARM-based tablets. I know Windows 8 will support ARM but as far as I know that means no legacy software support and Windows without legacy software support is not something I want to use, especially on a tablet.