Actually you can transfer harddisk with Windows XP to any new computer or same computer replaced with a new motherboard.
My 4 years old motherboard condemned two weeks ago and I was quite worry for re-installing a fresh copy of Windows OS and more than 30 softwares.
You still need to install all drivers come with new motherboard for Windows XP to run properly. I repaired Windows OS from the Windows XP CD to detect new motherboard and install all necessary drivers.
In Windows XP, you have to re-activate the OS after installing new hardware like motherboard. Unfortunately, the user cannot access Windows XP and re-activate it by phone in or internet connection.
I have followed the instructions in the link below to log into Windows XP and re-activate Windows XP online.
1. Start the PC into Safe mode with command prompt
Power on the PC and press F8 right before Windows begins to load. Select “Safe mode with command prompt”
2. Run Explorer from the Command prompt to start Windows
Once the Command prompt loads, type in “explorer” to start Windows within Safe mode.
3. Run “Rundll32.exe syssetup,SetupOobeBnk” from the “Run” box.
Now click on “Start” and in the “Run” box type “Rundll32.exe syssetup,SetupOobeBnk”. Press Enter. This will re-set activation to 30 days
4. Modify the wpaevents folder in the Registry.
Once more, click on “Start” then go to the “Run” box and type in “Regedit”. Make sure that in Regedit you are highlighting “My Computer” at the very top. Now go up to “Edit” then “Find” and type in “wpaevents” then press Enter. Right click on the “wpaevents” folder and go down to “Permissions”. Highlight “User” and place a check mark in the box labeled “full control”. Click “Apply” and exit regedit.
5. Modify the C: drives permissions.
Now double click “My Computer”. Right click the C: drive and go down to “Properties”. Now click on the “Security” tab and modify “User”, “Administrator”, and “System” so that they all have “Full control”. Click “Apply” and reboot the PC.
6. Run Windows activation
Now Windows activation will run and the PC will become usable again.