Label is used in this theme to display time and date. Check out it's readme to discover the many other uses of Label.dll
The winamp controls are provided via the use of Dynamp. It will detect which version of winamp you have (2 or 3), and works with either version. Label provides the winamp text display. Be sure to set your winamp to "Scroll song title in the windows taskbar" for the label display to work correctly.
Lswchanger loads the included wallpaper with this theme, automatically detecting the correct screen resolution. If you'd rather not have this feature you can disable it quite easily.
Open up the theme-step.rc and browse down a few lines to: "LoadModule $ModulesDir$lswchanger.dll". Just place a comment in front of the line like so: ";LoadModule $ModulesDir$lswchanger.dll" and save the step.rc.
Recycle Litestep and the wallpaper module is disabled.
Tasks and Taskbar3 are used to display the open tasks. Which module is visible depends on which mode the top bar is in.
Mzscript is the premier Litestep scripting module and runs "behind the scenes", enabling advanced functions like the bar toggling.