My 2 cents on the bands you mentioned that I have heard:
Burzum - what is all the fuss about? badly produced, and rather dumb "black metal", badly recorded, and with only occasional moments of that elusive mysterious greatness
In Flames - excellent melodic death stuff, get anything up to and including Colony. Favorite CD's: Jester Race, Whoracle (i dont know their earliest stuff that well). Dont like their new stuff at all, I have Clayman but it sux major, and I'm not getting their newest CD, they can go to hell for all i care.
Amorphis - the old stuff was pretty good, I really like the Black Winter Day song
Vader - Peter & co play some monsterously fast and heavy stuff. Doc (drummer) is probly one of the best (in terms of speed and accuracy) in the scene. Not the most creative stuff on earth, nevertheless always manages to bring pure aggression out of me.
oh, and see them live, they're a fuckin tank waiting to roll across your corpse
Old Mans child - very fun blackish, trashy, slightly symphonic metal, with keyboards and such. Satan rulez and all that shit type message. Pagan Prosperity and Ill Natured Spiritual Invasion are my top cds. Ill Natured was one of my favorite Cd's for a long time. Very well produced.
Children of Bodom - very technical, fast, with keyboards. Very melodic. I like their Hatebreeder CD. Some of the best guitar work, but unfortunately after a few months i have put it aside and havent listened to it since. Personally, i think their music lacks something that would make you spin the cd again after a few hundred listens.
Zyklon - someone described it as angry Emperor who cant find his keyboards. If you liked emperor, and myrksogg, you cant go wrong with this cd. Highly aggressive blackened trashy death. I dig the vocals too.
also to check out: dimmu borgir, borknagar, ulver, at the gates, novembre, kat