I`m in the process of putting my favourite tracks into iTunes before getting rid of the CDs. I have just been told by a friend that I should keep them because they might go up in value one day. He said he purchased a load of vinyl albums in the 90s for 50p at a boot sale and they are now worth £30 each. I`m not sure about that though as people don`t have the same sentimentality about CDs as they do about vinyl. Just wondered what others think.
A friend recently dumped a whole load of CDs and sent them off to Magpie. He got an average of 30p for each one. Vinyl, yes, that's more collectable but CDs? Maybe not so much. Check with Magpie how much you'd get for yours
Note that depending what method you use to "rip" the music off the CDs you will be losing quite a lot of sound quality.
Formats like mp3 and mp4 compress the files to make them smaller, but you lose some of the sound quality.
If you want to keep the sound quality rip them as FLAC or some other lossless format (they are larger files but I am not sure if iTunes supports FLAC).
But if you ever want to hear your songs in high quality format again in the future then keep the original CDs.