Both are fine. The only difference may be that you can rip tracks from a CD at a higher bit rate than MP3's you may purchase or in a lossless format such as a WAV file.  Some people wouldn't notice the difference...or even care.

However, one thing they both have in common is that they are protected by copyright laws.  You need to be aware of these when making decisions on how to use media.

In a nutshell...you only have the right to use them (in part or whole) for your own private uses and enjoyment, assuming they were legally purchased in the first place.
You do not have the right to play any part of them in public, or to distribute to the public.

Only the sounds in the MAGIX soundpools, and any sounds you create yourself, are legal to use for public performance, or for profit, without the expressed written permission of the copyright holder.