I think the standard way to do this on XP is to go into device manager and uninstall everything. Then, turn off the pc and do the hardware swap. This way the old MB drivers should be less likely to "ef" with the new setup. Seems like a reasonable way to do it on Windows 7 too. (I've never been considered the BRIGHTEST bulb in the pack, though...so..ymmv)
Good luck and let us know how it works.