Help ! VBR audio to CBR audio - How to ?

Help me please.

I need to know how I can decompress a VBR audio and then compress it then to CBR audio.

Any help would be great. Thanks in advanced

use a program that converts .mp3's to .wav's (like Winamp) and then use a encoder to create the .mp3 again. the quality may not be as good as the original mp3 though