?

I've got alot of music on my computer, ~12k songs after trimming down my library. I can only fit about half of this on my iPod, and Ive only got 14gb left on my computer. Alot of my music is 320 kbps, which i know is pretty inefficient and wastes alot of space.

Basically, i want to convert my 320 kbps songs (and i also have some songs that are 1000 kbps and upwards for some reason ) into VBR, so i can stop wasting so much memory.

Does anyone out here know any applications or websites that could do this? An application would be preferred because it's doubtful that a website would let me mass convert files and i've got alot of music to deal with right now.

It'd be nice if you knew a free application that could do this, but I guess if It will cost me a few dollars i'll deal with it.

Any help is greatly appreciated