OS: MS Windows
Statistica is a very comprehensive statistical software. Design of experiments, process analysis, quality control, Weibull analysis and much more are available. Not inexpensive, but this is a tool worth the price when reliability is at the forefront. A nice on-line statistical book and advisor is freely accessible.
OS: Unix and Linux
Mandrake probably the easiest installation on the market of the Linux operating system with multilingual capabilities. Linux is no longer a geek's only OS. A very low cost operating system including the manual.