The only ones that can be used as posable models directly by Poser are ones specifically stated as being Poser "Characters" or "Poable props", and such. I'd reccomend looking on here, in the Freestuff, under "Character", or in similar places on similar sites, like the 3D Commune (although almost everything there is here too...)

Remember, kids! Napalm is Nature's Toothpaste!