probably... stupid apple with there crappy support.
you shoud be able to boot from a CD.
try booting into Single user mode (i forget how, someone post it), and type
fsck -y
it will repair stuff
do it 2 or 3 times and try to boot...
wah? Is longhorn a MAJOR wrewrite? like OS X was to OS 9? if so, that could kill M$, they have so many apps for Windows, that most might not get to Longhorn... or whatever... unless they put this environment that dual boots into XP to run WIndows apps... >.>