I like MediaMonkey, like iTunes but better (much better for tagging).
Plus another for MM. I bought the gold version, and it's fantastic for full management of all your music files for tagging, syncing devices, playing, converting etc. You can also check which files have tag errors of a heap of different types. It also rips, although I use Exact Audio Copy for that.
Am just going through the process of re-ripping all my CDs to flac, once that's done I'll tidy up tags and embedded artwork with MM, then convert a copy to MP3 for the car.