Really cool post...I really like Nightwish too, but with Tarja as a singer. I have all their discography with Tarja and they were indeed one of the best symphonic metal bands...powerful, melodic and original...until they changed vocalist and all went to crap...but well, at least they made many good albums with Tarja we can enjoy...I made a post a while ago about this topic if you want to check it out...
http://blog.bitcomet.com/monti84metal/post_11850/
Definitely got my vote...