I got the MusicBrainz Tagger and it worked pretty well. I dropped 24,000 songs in it and it was able to correctly ID all but about 6000.
I also read on the MusicBrainz site that they aren't going to support the Tagger any more and to get the Picard version. I tried that one out and it was able to ID about 2000 more. The UI on it sucks though.