Admit you're going to visit lens lust often, and buy the lowepro 200 bag
Op something strap
Don't get talked into anything faster then an Ultra II card. D50 write speed is slightly faster the I, and slower the II. I won't start the debate on many smaller cards v 1 large card. I have (2) 1G, and (1) 2G. Also, the camera mis states how many photos fit on the card, by quite a bit.
Copperhill sensor cleaning kit. Sensor will get dust, just when and how much.
Shoot raw or raw + jpg from the beginning. Figure out how you're going to find one picture in 10,000, because you'll be there sooner then you expect.