Most times you can get away with just doing it but I noticed a marked increase in speed and stability when I reinstalled 98SE from scratch. The other problem you may have is trying to tie down problems since you won't know if they are caused by faulty hardware or a driver hangover.
After changing the hardware, install the new motherboard drivers and check the System Properties device list in safe-mode for conflicts and any mention of items for your previous Motherboard. Just remove them and reboot. The rest of your hardware should catch up but any probs, then remove the old drivers and reinstall.
Have a good read through the motherboard manual to check your BIOS settings before you fit it, they will be set at default and, despite manufacturer's best intentions, can cause problems. A reasonable BIOS explanationa and guide can be found click here (left hand menu)