There are free sound samples here. Sound good samples from that page . They're free for non-commercial use I believe.

Graphics: hmm, what sort? If you're after tilesets then there are a couple of links provided by cairnswm for me in the thread Free Tiles?. I might have one or two more at home - I'll have a look. Otherwise, you'll have to be a little more specific about what type of graphics you want .