hey, so your trying to convert a cd mucis file to an mp3 file. if you have a cd then you can get winamp and rip it to your hdd as mp3 or mp4 files. if you are ripping it for an ipod you need to rip it to mp4 if you are planning to play it on a mp3 player then you obviously need to rip it to mp3 format.
don't use winamp or itunes to rip your audio CD to your HD. use EAC (exact audio copy). It is the best ripper on the market period. It is also free. When combined with the LAME mp3 encoder using VBR (variable bitrate) settings you will get the best quality possible from mp3s. we have a guide on how to setup and use EAC here: http://www.afterdawn.com/guides/archive/mydeneaclame.cfm
As a matter of retoric... .CDA isn't an audio format. PCM audio is what is used for audio CDs. While I love the Mp4 format it isn't required for the iPod as the iPod supports Mp4, Mp3, Apple-Lossless, and WAVE files. Ced