[daveymck]

Others to try on the heavy front

In Flames
Dark Tranquility
Soilwork
Children Of Bodom
Norther
Mendeed
Sentenced
Edge of Sanity
(if you like this lot start going through the bands at Swedishmetal.net)

More Prog Metal

Anathema
Opeth
Riverside
Borknager
November Doom
Coheed and Cambria

More Traditional

3 Inches of Blood
Trivium
Blaze
Cradle of Filth
Dragon Force

The new Stone Sour Record is pretty good as well, I think the last Slipknot is pretty decent as well but might not get past their image.

Some more Goth metal stuff some has operatic vocals which may be a problem.

Nightwish
Lacuna Coil
Tristiana
After Forever
Epica
Crematory
Deathstars

Also some older bands have record out recent Exodus, Death Angel etc.

Most of these you should be able to get samples on myspace or videos on youtube.

Also try Dimmu Borgir and Emporer are black metal but at the more listenable end, can give more recommendations if you like these.