Automating jobs on the go

I want to learn how to write small, customized programs (scripts I guess?) that can be popped out in a minute or two to automate cumbersome or annoying tasks as they come up. Things like searching and renaming large batches of files, keeping tabs on a web page and logging changes, pulling out text of specified format or content from a database or highly-formatted source, etc. It's most important that these things can be made and run on any given Windows machine (think fresh install), with OS X and in-browser support being lower priorities. Mobile OSes aren't important.

Given that aim and those criteria, in which language should I learn how to do this and why?

So does Windows simply not natively recognize any languages, thus the need to install Cygwin despite my having said "any given machine" and "fresh install?" Or is all of this empty posturing from most replies meant to conceal that you guys just don't know much of anything about the OS?