Hard Drive migration, again.

Got a client who recently ordered a replacement PC. Last week the power company turned off the power to the industrial park without warning anyone and as a result another PC at the site seems to have died.

In a bid to get things up and running as quickly as possible I would like to know the following;

When I take the IDE drive out of the old-to-be-replaced system and install it in the new chassis I get STOP 7B errors.

Would a repair install fix this? (I dont want to do it and end up friggin everything up).

Also this post http://ask.metafilter.com/94202/Move-HDD-with-OS-to-a-new-computer talks about a similar situation with Win2k that seems to make sense. Has anyone tried this and does it work?

Is there a way to get the SATA drive from the old killed-by-the-power-company PC recognised and bootable from the old to-be-replaced (now a barebones) PC?

Both systems are XP Pro and properly licensed