Lower Bitrates

Hi guys
i have been scanning over the site and can't seem to answer my question on my own. i have a blacberry phone and playbook. my question is, with the majority of music downloads out there coming in a bitrate of 320 i am looking for a program to lower them to 128 or 192 ish to save space on both devices. i know i could search and search for the song with those rates but there not always available. does anyone know a good program to buy or freeware? does nero have that option?

thx guys
keith

 

I use Audacity for editing my music.