More LaTeX Info (Cambridge)
MiKTeX (LaTeX implementation for Windows, there are standard implementations for Unix/Linux)
WinEdt (one of several LaTex friendly text editors for Windows)
TexnicCenter (another great editor for Windows)
MacTex (Mac Tex distribution)
TexMaker (cross-platform editor - including MacOS)
Ghostscript/ghostview (postscript interpreter and viewer)
Comprehensive TeX Archive Network (CTAN) contains many other *TeX distributions, tools, packages and documentation.