I found the tutorials provided with P6 (and I presume P7) also very usefull.
Their manual, on the other hand, is only usefull AFTER you know what you are doing and only need to look up  some detail like a definition of a particular parameter etc.
I also highly recomend the book "Practical Poser 7". (I bought the one for P6 'cause I only have this version, but I got the P7 book from the library and it's even better.)

Also, there is lots of free tcontent available to start learning with, delay large expenditure till you know  a bit more...

Have fun

"I paint that which comes from the imagination or from dreams, or from an unconscious drive. I photograph the things that I do not wish to paint, the things which already have an existence."
Man Ray, modernist painter
http://artpearl.redbubble.com/