usually if you switch you motherboard it will result in xp not booting because of the different IDE controllers, unless you do 1 of 3 things
1) if you are swithing the board with the same IDE Controller (ie intel to intel or via to via)
or
2)Update the current IDE drivers to Standard Dual IDE Controller before the switch and windows will boot up and redetected everything
or
3) do a repair install of windows xp (never tried that personally)
I've done it both 1and 2, but it still better to do a fresh install when switching the motherboards.
Dahak