You don't need to invest anything in vitality or spirit. You get upgrades each level - I forget the number, between 4-8 points each level. As you advance, you can use charms and enchantments as well as various weapons will boost them. So IMHO adding to those two stats is a waste.
I think both my vit and spi are under 4 - and they're only past 1 because I've added charms. And both my HP and mana are over 400.
