Xilinx

About

 * Who is Xilinx? http://www.xilinx.com/
 * What FPGAs do they offer? http://www.xilinx.com/products/silicon-devices/fpga/index.htm

Development Environment
There is a gigantic development environment you have to download and set up to get started. Be not afraid, here's what to do:

Windows
Download the Windows installers here and follow the instructions

Linux (Ubuntu)

 * Download the Linux installers here