selling a camera - how to?

i've concluded that i need to sell my thrice-used-in-three years SLR camera and buy a digital one (so i can compete in this kind of nonsense, obv: THE ALL FUN ALL THE TIME GIGANTIC SICK MOUTHY VERSUS STEVEM CANON IXUS 430 VERSUS CANON IXUS 500 SPANKING NEW DIGITAL CAMERA PHOTO SHOW OFF WAR WARNING FUCKING BIG IMAGES ). but how to do this? should i just walk into jessops and see what they'll give me? i'm guessing i'd be better on ebay or amazon, but i don't really have much of a clue about either. help me!