Spie, if you get the option, if you get a chance pick up the Fallen album; superior to 'The Open Door' well IMO.
As mentioned Nightwish are also awesome, although you might find it easier to get into the latest Album; Dark Passion Play, as the new singer is a little easier to get into, Once is also an awesome album though

Within Temptation are actually worth a mention here, as they're a bit like a slightly more symphonic, heavy Evanescense (and good live).
Openmindedness with music is a good thing; some women make absolutely brilliant singers combined with the right band and attitude!
Sonata Arctica are actually pretty good but not what you're after. Different music style
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Like a true heretic, I'm gonna admit I quite enjoyed HIM at Metallica 07, even if they were booed; you could actually hear the music up in the stands unlike Mastodon and BFMV which sounded like a wall of bass and noise! That said I think they can be boring live. Metallica kicked the ***p out of everyone else there though, got some pictures somewhere from my old shoddy digicam.