How to achieve in Photoshop 5.5 an effect like this (without buying any expensive addons):

I think that some filters were applied here on original photos.
By the way, very long time ago I saw a tutorial which showed how to do this (I could swear it was a Photoshop tutorial). Unfortunately, the only thing I remember from that tutorial is the picture that was used to work on: it was a picture of a slightly freckled boy looking directly at the camera, in front of him was a table with bread and bottle of milk and behind him was a cow and green trees. If only I could remember where I found it.. There are tons of tutorials about turning a photo into a sketch, but this is not a sketch, it's illustration.. Anyway, maybe someone knows the technique...
