All my free space is taken by sda1 (ntfs), sda2 (ntfs), and sda3 (ntfs). Under Device for boot loader installation, it says that sda1 and 2 are both Windows 7 (loader), and sda3 are Windows Recovery Environment. I really don't want to mess up Windows, what should I do? I'm trying to run it as a dual boot, and have one hard drive.
If you installed Windows with click-click-finish mode, then it took up all your space for Windows the way you mentioned. You have to repartition the main partition (the largest) inside Windows (right-click on My Computer, then Management, then Disk) to make space for your Ubuntu install.
First you need to make sure that at least 10-20 Gbyte is free at all on your disk, but more is better. If you have sufficient free space then shrink the main Windows partition to 10-20 less than its current size.
Based on the fragmentation of your disk (and the placement of the files and the size of the disk) this could run several hours.
Now that you have a partition with free space, you can install Ubuntu (which will split this single partition into 2 to 5).
you can try Wubi istalator from windows, you find it on ubuntu website.. here is link http://www.ubuntu.com/download/desktop/windows-installer