Is it bad turning pc off by mains?

[TheMajor]

what you guys are failing to mention is that doing a hard shut down is horrible for windows. when you shut down correctly, windows has a chance to dump all of the system files back where they are supposed to be. turning off your pc like that can corrupt windows. and we all know how easily windows corrupts...

Windows can handle that.
However, Windows can not handle it if you turn off the power while is is shutting down or booting up. That will corrupt your XP sooner or later.