Carrie, I'm not sure here...Photoshop Actions (scripts, macros) are new to quite a few users, so please forgive me if this sounds like a lecture - with luck this may help others, if not yourself. <g>
Action files need to be decompressed and if on the PC must also end in a .atn filename extension.
Although they are cross platform, some users distribute them to Mac with no .atn extension and sometimes .sit compressed, while PC users may distribute a .zip compressed file with the action having a .atn filename extension. Some users just distribute a .atn extension and .zip archive to serve both platforms.
Actions can reside anywhere, and are loaded into the Actions palette via the Actions palette menu. When loaded into the palette, they are stored in a temp file with your other settings in later versions of Photoshop. If you change an action and wish to save it back to a .atn file, then the save Action command from the palette menu must be used (as the Action is in the temp file and not a live link to the original .atn file that was loaded).
Unlike plugs/filters - .atn files do not tie up memory by simply loading them into the application.
Actions are usually work from older to new versions, but the simple act of saving an older action from a later version of Photoshop will render the action unusable for earlier versions, even if no edits were made to the action (each version tags the file with a code which locks out earlier versions).
More on actions can be found here:
http://members.ozemail.com.au/~binar...V_links.html#A
Hope this helps,
Stephen Marsh.