You could write your scripts in Tcl.
the syntax is simple and closer to
what you'd expect from a script;
it is cross-platform, and will run on all major platforms;
you can easily create simple GUIs for your scripts in Tk, which will also work everywhere and use native controls;
for the Windows-specific functions,
you can use Twapi (Win32 API
bindings).
you can install a Tclkit, which is a single file that is the whole Tcl distribution. There's no lengthy install process or hidden files or mysterious directories;
- you can easily put a linux, windows and mac runtime on a single flash drive so you always have an interpreter handy even if there's not one installed locally.