.... and rest for /home.
There is an alternative that I like better. Just install the entire OS, including /home, on the first partition (I usually only use 16 or 20GB but you can use 40). Then, make the third partition a data partition. Mount it on /mnt/DATA, set the permissions appropriate for your user(s), and then make your main data folders on it, like MUSIC, VIDEOS, IMAGES, DOCS, etc. Now symlink the data folders into your user's home folder.
The reason to do this -- all those hidden "." configuration files in your user's home folder will stay with the OS. If the OS needs to be re-installed, or if you choose to multi-boot sometime, the "." configuration settings will not cause problems in the new or other OS.
Just my two cents' worth.