Renaming Files/Folders
Overview
Both operating systems allow you to rename files in the filesystem:
Select a file and hit the Return key (OS X) or F2 (XP) to instantly rename it
Click, pause and click again on a file's name to rename it
Open a Get Info (OS X) or Properties (XP) dialog
Mac OS X
While OS X does not facilitate batch renaming of files directly from the Finder, Apple does bundle several useful file renaming AppleScripts which you can access via the Script Menu. Scripts will execute against whatever files you have selected:
Add to File Names
Add to Folder Names
Change Case of Item Names
Replace Text in Item Names
Trim File Names
Trim Folder Names
In addition, OS X users can use Automator to quickly create a workflow that batch renames their files:
Select the files you wish to batch rename from the Finder
Control- or right-click on your selection
Choose Automator > Create Workflow. This will launch Automator and attach the files you have selected to a new workflow
Drag over the batch rename files action
Click Run
OS X also permits renaming of busy (in use) files. As soon as you rename an open file in the Finder and switch back to application it is open in, its name in the titlebar (and Save dialog) will adjust accordingly. Unfortunately, OS X lacks the ability to rename files/folders in any Open/Save dialogs, so taking advantage of this feature requires switching to the Finder, interrupting one's workflow.
Windows XP
Thanks to DJVirgen for the following info
XP has a rudimentary method to facilitate batch renaming. Select multiple files, right-click on them, and choose Rename. Type a new filename, and it will apply to all selected files, numbered sequentially. For example, say you have these three files:
sun.jpg
moon.jpg
mars.jpg
Right-click on sun.jpg and choose Rename. Type in "My - sun.jpg" as the new name. Your files will be renamed to:
My - sun.jpg
My - sun (1).jpg
My - sun (2).jpg
The obvious flaw in this method is that it does not permit a user to enter in a "base" file name to be appended to all of the files; rather, it renames all of the files the same full file name as the first, plus a sequential number. The original names of the files will be completely overwritten.
Power users could execute the following script at the Command prompt to achieve the same effect:
for %x in jpg do ren %x "My - "%x
However, this script will execute against the entire contents of a folder, rather than just the current selection.