huh? whats you q again?
if you replaced your mobo with a diffrent one (diffrent chipset and model etc) then yes you will have to reinstall.
Not necessarilty, I have found that 9 times out of 10 it's the ide drivers that fall over and windows XP doesn't like it. If, prior to changing mobo, you set the ide drivers to default windows drivers, you can get away with it (usually). Windows then picks up the new chipset and assigns drivers.
This is well useful if you want a quick performance comparison between your old board and your new one.
It certainly won't hurt to try it!