Mass reencoding program OGG -> MP3

Well i'm looking for one of these, need to convert about 60 GB of OGG files to MP3, i know OGG is very good as a type but the program i need the files for does not support OGG so i need to either input WMA or MP3, and since i find WMA crap... i'll go for MP3.

Anyone able to link me to such a tool that can:
Take a folder with ALL subfolders and output it to another folder and SAVING the folderstructure in the procces?

so it basicly needs to like "copy" the directory tree and just convert the OGG to MP3's without my manual interference :) 60GB is quite a lot so don't intend on babysitting the computer while its doing his thing :)

Foobar will do a mass conversion.