iTunes won't import MP3s from PC into library

I have ripped a large number of CDs into my iBook and iTunes plays them all as well as showing them in the library, playlists etc.. no probs...

Have laboriously transferred hundreds more previously ripped onto a PC as MP3s...

If I look in the folder where I put them, they are all displaying the iTunes green music file logo, with .mp3 filenames

iTunes will open to play a song if I double-click it

even putting all the MP3s in the same iTunes Library folder as my ripped AAC files does not make iTunes show them in the library, so it does not play them on random selection and I cannot put them into my playlists...

Is there a way to make iTunes see these files, other than import them one by one and converting them individually to AAC files (for which, frankly, EVERYONE'S life is WAY too short...)

What did you rip them with on the PC?

I'm not sure if this will work, but try File > Add to Library and then select the folder in which you have all of your songs. I'm sure it's going to import all the songs in that folder, not sure about the nested folders. If it doesn't, I'll send you an automator action that will take care of it for you.