iTunes 6 and id3 tags

Hopefully someone on here knows iTunes passably well.  I am fairly good with computers, as i suspect most of us on here are, and I have a large music collection (about 14.6 Gigs).  I prided myself on the fact that all of my music is in mp3 (and thus sharable) format, and that every song had a basically full id3 tag (author, album, track number, etc).  I recently got an iRiver h340, greatly superior to the iPod, and was shocked to discover that almost none of my music is correctly tagged outside of iTunes.  I am understandably annoyed about this, and was hoping there was an easy way to get the correct information in without doing it manually.  Hopefully someone here can help...

Thanks in advance.

Now that you can buy movies from the iTunes Store and sync them to your iPod, the whole world is your theater. With a 30GB or 80GB iPod in hand, those movies fit comfortably next to TV shows, new iPod games, podcasts, audiobooks, photo albums, and, of course, an entire library of music — up to 20,000 songs, in fact. Now starting at $249, iPod is a pocket-size prodigy.

What's a computer?

OP here, great, an ad.  Thanks, I can watch movies on the iRiver too.  Buzz off.

Your viral marketing powers are weak, old man!

Get a mp3 tagger, and tag them id3 2.3.
Foobar (the music player) works well.
Same with mp3tagger.

Each one of you faggots must get a Mac and leave my /comp alone.