Heavy Metal

[Maddolis]

Children of Bodom are pretty much heavy metal/power metal, although many people and sites (including wikipedia) will lead you to believe that they're melodic death metal. Honestly the only thing death metally about them are the vocals- but that can also be said for a few other "melodic death metal" bands.

anyone can recommend me some good Heavy Metal albums as a start off?

Depends on what your tastes are. It's probably best to start off with classics like these:

Heavy Metal/NWOBHM
Iron Maiden - Number of the Beast, Powerslave
Judas Priest - Sad Wings of Destiny, Screaming for Vengeance
Manowar - Hail to England, Battle Hymns
Black Sabbath - Black Sabbath, Paranoid
Dio - Holy Diver

Power Metal
Lost Horizon - A Flame to the Ground Beneath, Awakening the World
Blind Guardian - Nightfall in Middle Earth, Imaginations from the Other Side
Helloween - Keeper of the Seven Keys pt 1 & 2
Kiuas - The Spirit of Ukko, Lustdriven
Kamelot - The Black Halo, Epica
Sonata Arctica - Ecliptica, Reckoning Night
Evergrey - The Inner Circle, Recreation Day
Firewind - Allegiance, Forged by Fire
Iced Earth - Something Wicked This Way Comes
Ensiferum - Ensiferum, From Afar (these guys are folk metal, but I decided to put them here so I didn't create another list with just two bands on it).

Progressive Metal (note: some of the following bands may be a fusion of 2 or many more genres, or, in the case of early Queensryche/Crimson Glory, not prog at all)
Queensryche - Empire, Operation Mindcrime, The Warning
Symphony X - The Divine Wings of Tragedy, V: The Mythology Suite, Paradise Lost, Twilight in Olympus etc...
Pain of Salvation - Remedy Lane, The Perfect Element, Entropia, One Hour by the Concrete Lake
Dream Theater - Images and Words, Scenes from a Memory
Crimson Glory - Transcendence, Crimson Glory
Ayreon - 01011001, The Universal Migrator parts 1&2
Devin Townsend - Terria, Addicted
Opeth - Blackwater Park, Deliverance, Damnation
Tool - Lateralus, Aenima
Shadow Gallery - Tyranny, Room V

Alternative Metal
Tool - Lateralus, Aenima (also mentioned under prog)
Faith No More - The Real Thing, Angel Dust
System of a Down - Toxicity, Mesmerize/Hypnotize

Thrash Metal
Slayer - Reign in Blood, Seasons in the Abyss
Metallica - Master of Puppets, Ride the Lightning
Megadeth - Rust in Peace, Peace sells... but who's buying?
Pantera - Cowboys from Hell, Far Beyond Driven (though FBD isn't thrash but groove metal)
Anthrax - Among the Living, We've come for you all
Testament - Practice what you Preach, The Legacy
Sepultura - Beneath the Remains

Melodic Death Metal
In Flames - The Jester Race, Whoracle
At the Gates - The Red Sky is Ours, Slaughter of the Soul
Dark Tranquility - The Gallery, Damage Done
Amorphis - Tales from the Thousand Lakes, The Karelian Isthmus
Amon Amarth - With Oden on our Side, Versus the World
Skyfire - Timeless Departure, Spectral

A few of these are considered to be the greatest metal albums ever (Number of the Beast, Master of Puppets etc), and a few are just personal recommendations. I (or many others) could select 50 greater albums, but I don't think that's necessary.
Better get listening!