When you are running the Ubuntu 13.10 DvD/USB, open a program called Gparted.
You can use this program to edit partitions on your hard drive. Back up any files you need from your E: partition because this will delete everything on it. If E: is a separate hard drive, you need to select it in Gparted by changing the drive in the scroll down selector in the top right.
To make the partition that you want to use available to Ubuntu, you need to format it to ext4. You also need to make a partition for swap. If you already have four partitions on the drive, you need to create a logical partition to hold these two partitions.
Delete the partition you want to use for Ubuntu by right clicking it in the rectangle viewer area and selecting 'Delete'. Now right click in the newly created empty area and select 'New'. If you need a logical partition, create it first by keeping the size the same and selecting logical in the partition type. First, you should make a partition that is for swap. Make it the same size as your RAM, 1024 x # of GB and leave all empty space to the left of it. The format will be called "Linux-swap". Now create another partition for Ubuntu; it will need ext4 format. When you are done hit the apply button (green check mark).
Now start the installer. When you get to selecting how to install Ubuntu, select "something else". In this screen, select the ext4 partition you just made and right click it, then select 'change'. Set the mount point as "/" and select ext4 in the drop down selection.
Make sure your boot loader is selecting the correct drive at the bottom of this window. If you have Windows on sda then the boot loader needs to be on sda; even if you are installing Ubuntu on a different drive.
This should set you up with a dual-boot with Ubuntu and Windows 7.