Welcome :)

If all you want to do is make "3D Art Images", then all you need is something like Poser or Daz|Studio, and a graphic program such as Paint Shop Pro, Photoshop or something else.

You can get Daz|Studio free from Daz3d here:

http://www.daz3d.com/i.x/software/studio/-/?

It doesn't have all of the bells and whistles that Poser does, but it's free and it will give you an idea as to whether you actually like using such software.  Better to try something free first IMHO.

If you like it, you can get Poser, which has more advanced ability.

The current version of Poser is Version 7.  However, if money is a problem and you still want to get Poser, you can still find copies of Poser 5 for sale for really cheap because places are getting rid of their inventory.

You can get a  new registerable copy of Poser 5 here for $50 USD

http://www.thebest3d.com/poser/

You can get Poser 7 here:

http://www.e-frontier.com/

Once you have the software, you need to know some basics. I have a mini essay for new users here:

http://www.renderosity.com/mod/forumpro/showthread.php?thread_id=2700214&page=1#message_2998380

Organization is paramount when you are dealing with 3D graphics, especially with programs such as Poser.  Your runtime folder (what holds your content that you use) will quickly grow and if you don't start out organized, you will quickly find that you won't be able to locate anything. 

Here is a post that shows how I manage my runtimes so that I can find things. There are lots of ways to organize, and each person quickly finds their own method, but here is mine:

http://www.renderosity.com/mod/forumpro/showthread.php?thread_id=2701937&page=1#message_3009076

If you eventually want to get into creating your own models IE: props, clothing, figures etc, then you will need to have a 3D modelling program such as 3D Studio Max, Hexagon or whatever other types of 3D modelling programs are out there.

"It is good to see ourselves as others see us. Try as we may, we are never
able to know ourselves fully as we are, especially the evil side of us.
This we can do only if we are not angry with our critics but will take in good
heart whatever they might have to say." - Ghandi