Just follow this Step by step guide on how to convert or extract audio from video to MP3 using Free Video to MP3 Converter.
This is a free software. There is no spyware or adware in it as far as I know. Its is safe to install and to run on any version of windows including vista
Step 2. Launch Free Video to MP3 Converter

Follow Start > All Programs > DVDVideoSoft > Programs > Free Video to MP3 Converter or just click the DVDVideoSoft Free Studio icon on the desktop.
The interface is very simple and self explaining. There is a field for input files, a field for an output path, and the list with preconfigured profiles.
Step 3. Select Input Video Files

Click the upper Browse… button to select an input file(s) from your computer.

If you convert many videos at one time it can be useful to save the list of them.
Just make the right click of the mouse and select the Save list… item or press Ctrl+S.
Step 4. Select Output Location

Click the bottom Browse… button. Choose the location where you would like to save a new MP3 audio file(s). Click Ok.
Step 5. Set Tags

Click the Tags… button to set tags for the output MP3 file(s).
In the Tags window specify the track number, title, artist and other parameters as you want.
Click OK to switch back to the main program window.
Step 6. Select Output MP3 Profile

In the list of Presets select one of the available pre-configured MP3 presets:
- High Quality (MP3, 256kbps, 48000Hz, STEREO);
- Optimal Quality (MP3, 192kbps, 48000Hz, STEREO);
- Standart Quality (MP3, 128kbps, 44100Hz, STEREO);
- Economy Quality (MP3, 96kbps, 22050Hz, STEREO).
Step 7. Trim Video

Click the Trim… button to open a new window.

Use navigation line and special buttons to set a start and end selection markers position.
Click OK to switch back to the main program window.
Step 8. Extract Audio from Video to MP3

Click the Convert button along the bottom of the interface to convert video to mp3 and wait just a few seconds.