Please refer to MS KB article 824125 (last reviewed 7/29/2003) and 287043 (last reviewed 6/6/2003).
Article 824125
HOW TO: Replace the Motherboard on a Computer That Is Running Windows 2000 or Windows Server 2003
http://tinyurl.com/j9u7
The article describes the steps that you must perform to reconfigure Windows to work with the new motherboard (upgrading an existing one or replacing a failed one).
Article 287043
"STOP 0x0000007B: INACCESSIBLE_BOOT_DEVICE" Error Message When You Start Your Computer.
http://tinyurl.com/qm9a
The resolution of this problem is same as the method of replacing a failed motherboard as in the article 824125.
Some have said this does not work but I have had a few successes (also on Windows XP).
On one occasion, I did not even have to do Windows update all over.
Yes, it is preferred clean installing Windows when you upgrade motherboard. But this is not always the best solution.
Back up your data before you try.
If the method of upgrading an existing motherboard does not work, use that of upgrading a failed motherboard.