I have an older notebook with a dead NiCad battery. Are they any potential issues with replacing this battery with a NiMh or LiIon battery? I know when I switched from NiCad to NiMh for my camcorder, I had to buy a new charger.

You always need to have notebook batteries specifically designed for that notebook model

AFAIK, you can never switch from one battery type to another

I read that notebook batteries are conditioned from the factory for the specific model of notebook they are intended for (b/c different models use more or less power)