@zeroG
You might want to look up a program called Mp3tag
Mp3tag - the universal Tag Editor (ID3v2, MP4, OGG, FLAC, ...)
This is a great, easy to use program to auto tag all your music. It has the option to look up songs off the amazon database and replace all your tags globally with the correct tags or just certain fields, including art work.
I really like it and it has allowed me to really clean up my music library fairly quickly. I keep all my music on a folder on my comp as a backup and Mp3tag will auto look up that folder each time you start it so its nice to keep everything organized.