Quickest Easiest ID3 Tagger needed !

[vim147]

I have 500+ music albums collected going back to Napster days on my external HDD.

I have them in folders for each album however not all are ID3 tagged correctly so in itunes it appears all jumbled up when i go into albums tab.

What would be the easiest and quickest way to ID3 them that requires least amount of clicks & selecting etc ?

Just want something that functions, not too bothered about cover art.