standard audio CDs are not compressed. they use linear-PCM format.
mp3 format is a type of compressed lossy audio. If you want to create an mp3 CDROM to play in your car for example, the files are compressed to begin with, so you can't burn an mp3 CD uncompressed.
if you are going to convert your audio CDs to mp3, there are a few things you should do in order to create the best quality you can. First, use EAC (exact audio copy). it is free and the best ripper there is. second, use LAME to encode the files to mp3. third, use VBR (variable bitrate) at a setting of at least 192kpbs.
we have a guide here on how to install, setup, and use EAC/LAME. you can find the link in my sig below.
If you already have mp3s on your computer, such as ones you have downloaded, you can't really do anything to change the level of compression. so just burn those to a CDROM to create and audio CD.
