Download some tracks by a band called 'Death', they are the godfathers of Death metal and they f'ucking pwn, unlike 'Cradle of Shite' and other such bollocks...
Of course there is classics like 'Led Zeppelin', 'Black Sabbath', 'Iron Maiden', 'Guns 'n' Roses' - and then going onto 'Pantera', 'Metallica' and 'Megadeth' like Drizzt mentioned
If you want something more technical and metal-minded, check out 'Slayer' and a new band called 'The Haunted'. 'Soulfly' are also heavy with a brazillian tribal influence.
If you wanna try stoner rock, check out 'Kyuss', (and the spin-offs 'Queens of the Stone Age and 'Fu Manchu') and 'Orange Goblin'.
If you like Emo/Screamo, then 'Finch', 'Funeral for a Friend', 'Hundred Reasons' and 'Taking Back Sunday' have some good sh1t...
'Incubus' older stuff is also pretty sweet, same goes for the 'Red Hot Chili Peppers'...
...And im not even gonna get into my punk collection
Three words to start you off 'The Sex Pistols'
Some songs:
Death - Bite the Pain, Flesh and the Power it Holds
Led Zeppelin - Kashmir, Whole Lotta Love
Black Sabbath - Sabbath Bloody Sabbath, Iron Man
Iron Maiden - The Trooper, 2 Minutes to Midnight
Guns n Roses - Paradise City, Welcome to the Jungle
Metallica - The Unforgiven, One, (Welcome home) Sanatarium, Enter Sandman
Megadeth - High Speed Dirt, Angry Again
Slayer - Angel of Death, Raining Blood
The Haunted - Tresspass, Bury your Dead
Soulfly - Back to the Primitive, Roots Bloody Roots
Kyuss - Demon Cleaner, Thumb
Queens of the Stone Age - No one knows, The Lost Art of Keeping a Secret
Fu Manchu - Godzilla, Squash That Fly
Orange Goblin - Land of Secret Dreams
Finch - Awake, Post Script, Letters to You
Funeral for a Friend - The Art of American Football, Rookie of the Year
Hundred Reasons - Falter, Silver
Taking Back Sunday - Cute without the E, A Decade Under the Influence
Incubus - Drive, Circles
Red Hot Chili Peppers - Under the Bridge, Give it Away
The Sex Pistols - Anarchy in the UK, God Save the Queen
Thats just a few to start you off
If I named all the bands and tracks I like I'd be here all day
Hope thats of use bro!