Download and install a media player that supports the FLAC format. Some media players that support FLAC are Media Monkey, VLC Player and Winamp. See Resources for links to these programs.
Right-click on the FLAC file you want to play and select "Open With." If there are no media player programs listed, even after you installed a compatible player, go to "Choose Default Program." In Windows XP go to "Choose Program."
Select the program you want to associate with FLAC files from the list of available programs and check the box next to "Always use the selected program to open this kind of file." Click "OK" to begin playback of the file. If you still can't see the program you want to use, click "Browse," locate the .exe file for the program, and click "Open." Playback of the FLAC file will begin after a program is chosen.
Download Xiph QuickTime Component (see Resources). This is a Mac-only program that makes FLAC compatible with iTunes.
Install the program to your Components folder, which is located under the Library folder of your account.
Quit and restart iTunes and QuickTime Player Pro if they are running.
Relaunch iTunes and drag the FLAC files you want to play into your library.
Double-click on the song name in iTunes to being playing the file.