Xilinx Webpack:
http://www.xilinx.com/xlnx/xil_prodcat_landingpage.jsp?title=ISE%20WebPack
Xilinx installation: http://www.princeton.edu/~shengqiy/Teaching.htm
Manuals for Xilinx tools:
http://www.xilinx.com/support/sw_manuals/xilinx5/index.htm