@ Reno: No.
Okay, you are basically looking at two things this could be. Based on the description, you basically want a band called Therion. Although they only technically have three members, their last album had somewhere like 180 musicians and vocalists appearing on it, including a full choir and symphony orchestra. Download the following tracks: "Nifelheim", "Typhon", "Abraxas", "To Mega Therion". Awesome band, in my book. Don't be indiscriminate though, as their earlier stuff is pure death metal. Albums after and including 'Theli' are what you're mainly after. I can't think of any other band that does this all the time, though several others have done it more one-off (most famously, Metallica's S&M, and possibly Cradle of Filth's Damnation and a Day, though that's pretty shite).
Alternatively, and more commonly, there's Symphonic Metal, which sticks to the band format but uses more overt classical elements than normal (Startling fact: A lot of metal, particularly European metal, is heavily rooted in classical structures) including lots of orchestral keys and pads, an above-normal number of vocalists, and increased use of devices like lietmotifs and classical sounding riffs. These come in a few flavours, Symphonic Black Metal (such as Dimmu Borgir or Cradle of Filth, but also less well-known (and better) groups like Illnath and to an extent Sigh) and some power metal, particularly bands like Rhapsody, Avantasia, Yngwie J. Malmsteen's Rising Force, etc. But also bands from many other metal genres, such as Doom (My Dying Bride, Virgin Black), Death (Matriarch) etc.
Also, you might want to check out Apocalyptica. They play metal, but they're a string quartet. I think that's pretty cool myself.
