Batch conversion - whats best for mac?

Hi

So I've got a load of m4b's that play fine on the ipod.  However I'm thinking of rockboxing my classic as I hate itunes (always have).  As such I need to convert the m4b's to mp3's.  I've tried the m4b file in rockbox and it doesn't want to know.  I've also tried converting to m4a and doesn't like that either.

Main reason I'm trying to do this is because I want the structure to look something like :-

MUSIC

Artist Name

Album

Songs

AUDIOBOOKS

Big finish (name of company as example)

Doctor Who (category example)

play.

So I have some work ahead of me.  I was just wondering if there was a good FREE mac osx batch converter.  I do have one way but it's a pita.  Basically use a program called audiobook builder to convert m4b to m4a. Then batch convert the lot from m4a to mp3 using switch.  If there's a quicker (preferably free!) way of doing it then that would be helpful.  I've got about 123 gigs worth of audio plays to convert.  It's either that or swear at itunes a lot as I try to sort the tags out (and even then I think I'd still prefer the structure above!).

Cheers

Thanks for both of those.  Familar enough with Max but only used as a ripper.  Had no idea it could batch convert as well.  XLD I'm less familiar with but have stumbled on it in the past.  

I hate Itunes with a passion, so to be able to rockbox the classic and dump the stuff in there in the format that I WANT and not some other way is quite appealing.  The annoying thing was was that I was at a crossroads where there's no advantage to either batch convert or retag (hate re tagging as well!).

Thanks again :)

Well this is annoying.  Unless I'm doing something wrong (possible) neither max or xld seems to recognise m4b!  So I'm having to copy the whole directory over (98 gigs worth of audiobooks alone in an hour!)and then chuck it through dbpoweramp which is nice, straight forward and seems to work.  This is the one area where the pc seems to be ahead of the mac (largely I suspect to the monopoly of the aforementioned hated itunes).

Cheers
 

Only problem with that is that I have a LOT of the m4b files.  Switch does seem to handle it very slowly on my core2duo mac.

On a related issue I have just run into a stumbling block in that the netbook I was using for the batch conversion got taken out by the usb drive that I was using for it!  Had formatted the drive to be seen by both mac AND Windows.  Everything was fine, came back to it now the netbooks fried.  Whoops.  Still it was on it's last legs but still (samsung nc10).

Cheers