Thinking about selling my CD collection = MP3

If you sell the CD's then legally you cannot play the music you downloaded. Falls into the same category of borrowing CD's to download. I know that this may not bother some, but it is one of the reasons to hold onto the collection. Another would be if a new better system was developed for downloading, computers seem to change often.

I'm not sure I agree with Davt's legal interpretation, but notwithstanding, I think you should do your MP3 transfer for now and just put the CDs in dead storage. For 2 reasons:

1.) You won't get that much for them. You'll get a buck apiece as a collection. Unless you want to sell them individually and your time isn't worth anything.

2.) You sound like a young person, so take a tip from an old person: the time WILL come when you'll wish you had kept them because they will have acquired new meaning/value for you (and some of them will possibly have become collector's items.)

Get some plastic (poly-cardboard) CD storage boxes cheap from Bags Unlimited and put 'em away. You'll be glad you did. Unfortunately I won't be here for you to thank me ;--)

Oh yeah, store the CDP too, if it's something decent.
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Depending on which country you are in, you may be breaking the law.

Agree with Nsgarch. The audio community is replete with members who sold off their vinyl collection in favor of those shiny little discs 15-20 years ago. Many of them are now wearing "kick me hard" signs on the seat of their pants.