What is this classic tune (2 second clip)

[Johnny|lucidcomposure]

Its part of a recent family guy episode. I know how the rest goes but I cant think what it was called.

Anyone who can shed some light ?

http://www.fstop11.net/forumdata/familyguyclip.mp3

 

[Johnny|lucidcomposure]

It's the Dies Irae from Mozart's Requiem.

My new friend