SDP,

asked the same question when I started... and I got told the same thing that kittykat46 said..
Basically the AV, Manual and sometimes the TV settings are truely all you will ever need. I found it hard to believe that a pre-setting would be better (being the stubborn farm girl I am).. so I did my own tests and sure nough.....lol.. the AV pictures turned out better..
The best thing to do is try them on the same subject and go from there.... My k100 Super seldome leaves AV mode but it is shortly going to discover M mode....
Good luck!! Kim