Resources
MIDI files for practice for the Mozart Requiem can be found at the following link:
http://www.cyberbass.com/Major_Works/Mozart_W_A/mozart_KV626_requiem.htm
Note that Cyberbass no longer allows you to download these files for free. However, you can listen to them while connected to their web site.
A good alternative is this site put together by John Hooper, which will let you download the files (but they include the orchestral parts as well as the individual vocal lines):
http://s119247422.websitehome.co.uk/midimusic/Mozart/Requiem/requiem.html
You can also download files for the Requiem, with lyrics, from this site:
http://nwc-scriptorium.org/mozart.html#mozart
These are in the Noteworthy Composer format, which you can play with the free Noteworthy "Viewer", downloadable from this site:
http://www.noteworthysoftware.com/nwc2/viewer.htm