Consequences of turning off computer during Windows Vista update ("Do not turn off your computer")?

"Likely, the update it is currently on will fail, but you can continue using your computer like nothing happened - You may want to run chkdsk on your hard drive just to make sure there are no problems.

Worst-case usual scenario - It is in the middle of updating a system file / half way through the process and a restart means it is missing as it is does not exist at the moment. However, Windows Vista is quite good at repairing itself and may boot into the recovery mode and roll back the update for you, so you will be out of action for a short while (probably under 30 minutes)

Utter worst case unusual scenario, it is updating a boot file (but not sure how many updates do this) and restarting will give the message ""Operating System Not Found"" or similar. In which case you will need to put in the original disk and do a startup repair or at very worst case, a reinstall of Windows."

"Worst Case: Your computer will no longer boot, and you will have to do a repair install from the OS disk. (Or, VERY unlikely, your disk will become slightly corrupted, so make sure to run a chkdisk /f after rebooting)

Best Case: Your computer will boot fine, and install the updates again perfectly.

edit: Just to be more specific, a repair install will not wipe any of your files or settings or programs away."