SP2 install woes

I've just tried 3 times to install SP2, every time it finishes the 3rd stage of "Installing Service Pack" then says it failed to install and reverts everything

It turns out that there are some lively threads about it at MS's answers site, an example is here:

http://social.answers.microsoft.com/Forums/en-US/vistawu/thread/3eeb8d59-bcd3-449a-be0b-18a6c0b92891

The reason for the grief is that a Grub installation for Fedora is treated as a corrupted boot sector by this SP, apparently I would need to "repair" (that's MS code for fuck up) my boot sector with the VIsta boot loader, and then reload Grub after booting from a Fedora disk once the Service Pack is installed.

Well done MS, another inability to mesh with the rest of the world. I was able to install Vista SP1 without problems so why is SP2 borked?

Evil Steve, because you can bet some chairs will die over this.