> "Hang on, aren't all Windows RT machines exactly the same hardware? How could there be differences between machines where an update would brick some and not others?" No. Microsoft Surface RT machines are built with the Nvidia Tegra SoC. Others, like the Dell XPS 10 use Qualcomm's SoC. I wish Microsoft had included some details about what machines/configs are bricking and which are not. I upgraded two Dell XPS 10 machines with no issues. And I haven't seen any conclusive patterns emerging from various forum posts and tweets complaining about problems. One possible delta in the environment to which the update is being applied is whether or not the 8.1 PREVIEW had been installed prior to the update. For example, I've heard that people who installed the 8.1 preview on a Dell XPS 10 had to remove the recovery partition before it would work. So, I can imagine an update process failing when it expects to find a recovery partition in place. But the number of these devices is pretty small and you think would be easily identifiable from the problem reports coming in. But I wonder if the problem is anything like this or related to the preview. OTOH, most people upgrading from the preview seem OK outside of having to re-install some applications.

Well the header at http://www.ubuntu.com/getubuntu/downloadmirrors#bt says 9.04, but the actual links below it are for 9.10.