How to convert FLAC audio to MP3 in Windows
While you will find many other paid tools to convert FLAC audio files to MP3, this guide will show you how to use just one free, open-source tool (which can also perform other file conversions) to convert FLAC to MP3: MediaCoder.
MediaCoder is a free, open-source media converter. It can convert most formats of video and audio. If you are looking for an open source FLAC converter, look no further than Media Coder. It is being improved constantly, and has the advantage of being open source. This means that it has support for most file formats. It can also help you convert audio for popular mobile devices (PSP, iPhone/iPod). It is fully standalone, which means that it does not depend on system codecs.
Note: Desktop has been advised as the location to save files in steps below because it is the easiest. If you know your way around drives and partitions, use any other folder you wish to.
Step 1: Download and install Media Coder
MediaCoder is free and open-source, which means that you do not have to spend a penny to get it. Download MediaCoder from here, and install it. After installing, start up Media Coder.
Step 2: Add File/folder
To simplify the process, place all FLAC files on your desktop. If you have more than one file, put it into a folder in the desktop.

After opening up MediaCoder, click the “Add” icon on top left corner to get a drop down menu. If you want to convert only one file, click Add file. If you want to convert a full folder of tracks, click Add folder. Click “Desktop” and add the file/folder.
Right-click on the file you added, and click “Set output folder”. A window will come up - click “Desktop”.
Step 3: Edit settings for conversion

Click on the Audio tab on left side (as shown on screenshot below), and then click on the “LAME MP3″ tab on the right side (also in screenshot below). Adjust Bit Rate to 5 and Algorithm Quality to 0.

Now, hit F5 (or alternatively, click Transcode menu on top, and click “start transcoding”. Your file will now be converted - sit back, and maybe grab a coffee if you have several files to convert.
FLAC: More information
FLAC is an abbreviation of Free Lossless Audio Codec. Lossless implies that no quality is lost while converting to FLAC format. This also means that the level of compression when using FLAC will be less. In contrast, MP3, a popular audio format, is lossy, which means that you lose some original quality while converting to it.
Most humans cannot understand the difference between FLAC and MP3 of a sufficiently high bit rate (we’ll talk about bit rate later). Hence, MP3 format is preferred for its space saving benefits. Another advantage of MP3 format is that it is supported by most digital devices - mobile phones, MP3 players, CD-walkmans, stereo setups and DVD players.
I wish there was some way to play Flac files in WMP. I have some songs in FLAC format which are of very high quality and i don’t want to change them.
You can play FLAC file in WMP by using a plugin:
http://www.xiph.org/dshow/
Seems to work okay, although I’ve only tried it briefly as I use Winamp anyway.