Proteus asked me to post these for ya'll.
This is one of the display tanks at my LFS. Tank is about 800g. It also has a sump but I am not sure how big that is.
http://www.plantgeek.net/users/ice/discus.jpg
For size comparison........Tre (The owner) is about 6 foot 2.
http://www.plantgeek.net/users/ice/discus2.jpg