For the symphonic classical, it's kind of hard to describe what specific sound I'm looking for, but here's a track sample of what I mean:

http://www.epitonic.com/artists/dimitrishostakovich.html

(The first sample on that page)

And for ambient, anything similar to Aphex Twin's Selected Ambient Works, Harold Budd or Brian Eno. Doesn't matter if it's instrumental or electronic, extreme minimalism is welcome too.

good stuff, but that is not ambient. That is real.

The GODS of ambient...

THE FUTURE SOUND OF LONDON

You must of heard of them if you like Brian Eno & Aphex.

http://www.amazon.com/exec/obidos/search-handle-form/103-6957681-9563857

Also go to www.pureacidmixtapes.com ...a lot of stuff there too, the have 2 compilations called Future Sound Of Ambient with a lot of Eno & London.

I don't know if these count as Ambient, but here goes:

Deep Travel - Doublestar Project

Humanity - A Guy Called Gerald

Children - Robert Miles

Insatia - Sidewind (came from a video game, heh heh) :D

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Other songs that are not Ambient, but I really liked:

Myst III:Exile - Myst III

La Petite Fille de la Mer - Vangelis (CD: L'Apocalypse des Animaux)

Adagio (performed by James Galway) - Tomaso Albinoni

Sora - Yoko Kanno

Sweet Rain - Bill Douglas

Going-To-The-Sun - Philip Aaberg