A. The new Media Player for Windows XP (MPXP) includes a cool hidden feature that Jonathan Usher, the group manager for Microsoft's Windows Digital Media division, recently revealed to me. As you might know, you can determine the format of the file names MPXP creates when you copy CD audio to the hard disk. Select Tools, Options, Copy Music, and click Advanced to set up a custom file name format. But what if you already have a lot of Windows Media Audio (WMA) files and want to automatically rename them by using your custom file name scheme? Thanks to this hidden feature, you can do so, although you must rename the files one album at a time. Here's how: Set up MPXP so that newly recorded music will follow the file-name convention of your choice (e.g., Artist Name_Song Name.wma). Then open the Media Library and select a CD album you recorded with a different file-naming convention. Right-click the album name and select Get Names, which will connect MPXP to the All Music Guide (AMG) Web site and restore the original artist name, album name, and song titles from the AMG database. Clicking Finish applies this information to the actual files, renaming them if needed, using your new file-naming convention. This process has one limitation: It works with only WMA files, not MP3s.