Hi,
Thanks for the help, I couldn't find much on the internet at all about it, but after working through the help files and the stuff on Alias site, I realized it was a lot simpler than i thought.
Now I see what Mike means and i just go to my Model's Alpha Channel (In Photoshop) and Contrl/drag it across to the background image to composite them.
I had problems before as I was trying to "select" the alpha channel with the magic wand, and do it that way. DOH!

Thankyou very much. Scraggy.