Geesh... what a rediculous thread this is.
To the original poster, here is my two cents
1) MP3 isn't a "quality", its a lossy audio format. It's quality can vary from absolutly horrible, to pretty dang good. The fact that it's ending quality is dependant upon the quality of the source, is irrelivant. That's not what we are comparring. We should assume the source is properly recorded and properly mastered. To bring that into the discussion is stupid.
2) Some people, including myself, CAN distinguish the difference between a source WAV or TDA file, and the most properly ripped 320 mp3 file. MOST people, (not audiophiles, etc.) cannot hear a difference. Being a musician of over two decades with an overly critical ear (sometimes I drive mySELF crazy), I can always tell the difference, especally in any track containing an accoustic drum kit. The sound quality of the kit's Cymbals are the first thing to go to my ears. And regardless of what some have said here, I would certainly be able to tell the difference in a blind test.
3) Lets say you ARE an audiophile with a very critical ear. That still doesn't mean that a 320 MP3 is useless. They take up very little space on a hard drive, sound pretty good, and are easy to copy/move/replace/backup, etc. Heck, depending on the MP3's use, a 128 MP3 might even work for you. It depends on its application!
Critical Listening in a nice quiet audio room, NO mp3 will be worth it. Jogging with your iPod with headphones... 128 would be just fine. See?
4) I myself, rip everythign to a losslesss WMA file. They're easily twice the size of a 320 MP3, but are just as easy to store and manipulate, and are indistuingishable from the source WAV or TDA track. That way I get the best of both worlds. A digital file I can copy and paste from player to player, or onto a DVD... AND it sounds as good as the source file. The disadvantage, is you will need a bit more disk space as the files are a bit larger.
5) Take everything you've read in this thread with a grain of salt, including this post.
Good luck!