Convert Large Music Library

Ok, I am about to pull my hair out over this. I have a very large music library, that I want to convert completely over to .ogg. Only thing is, I cannot find anything at all which will do that. Does anybody have any suggestions?

ok one thing is what ogg. ive heard of it but what is it. download Advanced WMA workshop

mediamonkey (free) will convert to ogg. i haven't been able to get it to see m4a's however.
scan your lib, go to folder & highlight, then rightclick 'send to (rip/convert)'