o.. just read your first post again..lol
I did it in PS CS2 which would be best in my opinion for any sort of editing. PNA will have selected just the child using the lasso tool, but i used the magnetic lasso when i selected him to edit the photo, then invert it and feather the selection and either completely remove the background and fill it.
I've never used photostudio but it dosen't look very good compared to Elements or PS in my opinion. If you are going to be doing alot of editing and really getting into it i would recommend getting elements or PS. Elements is much cheaper than PS but lacks some proffesional features however is probably ok for most people.