Moving a hard drive w/ a Gateway-installed OEM Windows XP to a new mobo

This issue involves moving a hard drive with a Gateway-installed OEM Windows
XP to a new motherboard.

Gateway has already told me that this "won't work".  What I'm unsure of is
whether doing so would cause a BSOD before I even see a Windows splash
screen appearing.  I would think that it should boot up into Windows, call
me a bad boy, and then offer me a way to set things right.  Seems logical,
no?  The BSOD mentions the problem is with the hard drives, advising me to
run a CHKDSK /F, which to my knowledge, can only be done from the Recovery
Console, which requires a password for the "Administrator" account, which is
unknown.  (I tried "" [no value], "admin", and "Admin" before it forced me
to reboot after three failed passwords.)  The owner of the PC has backups
and isn't opposed to having to purchase a new WinXP license, but is
concerned about having to reinstall *everything*.

Other details: Original Gateway's mobo & CPU were fried when the owner tried
to reinsert the CPU and "missed"; don't know if sparks were involved.  When
I removed the hard drives from the Gateway box, I kept the IDE cables
attached to the drives, and changed no switches on them; the BIOS on the new
PC correctly identifies them.  I have burned a copy of the Ultimate Boot CD,
and will (attempt to) run diags on it tonight; maybe the drives got a bit of
frying along with the mobo and CPU?  Maybe I should try a new IDE cable for
the drives?

Gateway's chat support directed me, with disclaimers, to
http://windowsreinstall.com/winxphome/installxpcdrepair/part3.htm.  Don't
know if that route would be better than the Ultimate Bood CD, as there
appears to be a risk of losing data.

Any advice would be appreciated.

- Dan