Partially reproduced from http://www.mostlycreativeworkshop.com/article11.html, please go there for the full article.
"So, you've decided to move your drive with Windows 2000 (or XP) to a new system, or upgraded your motherboard, and you now get the dreaded blue screen of death before the operating system gets to the desktop. All you get is a STOP 0x0000007B error (INACCESSIBLE_BOOT_DEVICE). What now???? Well, here's what you need to do..." "Well, the first thing you need to do is to get the system working again, so, put the system back in the original working configuration. If you changed the motherboard, change it back to the original. If you moved the drive to a new system, place it in the old one."
As I come across this often enough and when I do time is usually of the essence- is to have a preconfigured BartPE disk with folders for each of the files for Windows 2000 SP0-4 and Windows XP SP0-3 and the necessary registry files included to merge them in easily while in BartPE.
"Now, for people that understand what they are doing, and how to do it, here are the "quick" steps: Replace the word Systemroot with your Windows install folder (ie. c:\WINNT or C:\WINDOWS) 1 - Extract 'Atapi.sys,' 'Intelide.sys,' 'Pciide.sys,' and 'Pciidex.sys' from 'SystemRoot\Driver Cache\i386\Driver.cab' (or SPx.CAB if it exists, where x is the latest service pack) (check addendum) 2 - Copy those four files to the following location: 'SystemRoot\System32\Drivers' (do not replace files already there) 3 - Merge the registry file found below (copy the text to notepad and save as a .reg file), or better, download it here 4 - THAT'S IT! Move it to the new system (or change the motherboard), and your system should start up. STEP BY STEP INSTRUCTIONS FOR THOSE THAT NEED IT: Replace the word Systemroot with your Windows install folder (ie. c:\WINNT or C:\WINDOWS) 1 - Click START, go to RUN, type in "CMD" (without quotes), hit ENTER 2 - At the command prompt, type in: "CD SystemRoot\Driver Cache\i386" (without quotes) hit ENTER "dir/w" (without quotes) hit ENTER If you are running Windows 2000, check for SPx.CAB (where x is the highest number), in the following steps, use the SPx.CAB instead of DRIVER.CAB (If you are asked to OVERWRITE any file, choose NO) "expand driver.cab -f:atapi.sys SystemRoot\System32\Drivers" (without quotes) hit ENTER "expand driver.cab -f:intelide.sys SystemRoot\System32\Drivers" (without quotes) hit ENTER "expand driver.cab -f:pciide.sys SystemRoot\System32\Drivers" (without quotes) hit ENTER "expand driver.cab -f:pciidex.sys SystemRoot\System32\Drivers" (without quotes) hit ENTER "exit" (without quotes) hit ENTER 3 - Merge attached Reg file... you will be asked if you wish to MERGE the contents with you registry, CHOOSE YES. 4 - THAT'S IT! Your system is prepared to be moved to another system/have the motherboard changed."
Other Potential Issues
For those running Windows XP w/Service Pack 1, 2 or 3, the proper locations for the 'atapi.sys,' 'intelide.sys,' and 'pciidex.sys' file are in the SP1.cab (or SP2/SP3.cab). The 'pciide.sys' file remains in the driver.cab file.
Issues booting or logging on afterwards
There are occasionally issues after this to do with the disk signature changing between drives. These can be rectified by this Microsoft Knowledgebase article. http://support.microsoft.com/kb/249321/
Intel to AMD CPU architecture.
If you get a blue screen at boot getting the STOP error: 0x0000007E after an XP SP2 upgrade after migrating moving from an Intel CPU to AMD