When I open the Xilinx product download page (http://www.xilinx.com/support/download.html) I see a number of different download options.
How do I know which individual product installation file I should download?
Xilinx has grouped the tools according to type of licenses we provide and by Operating System (OS).
The Vivado Full Image download is an all-in one download, it contains the installer for all editions along with SDK and Lab Tools.
If you will only install on a specific OS, download the OS specific download.
The OS specific download includes an installer for both a 32-bit and 64-bit OS of that type.
To use the Web Install Thin Client, and download only the files you will actually need, download the Operating System and bit-width which matches the one on your machine.
When choosing an Install client, please do not choose a 32-bit client if you are running a 64-bit operating system.
If you wish to install 32-bit applications, it can be done from within the 64-bit client.