Your not going to get CD quality on a SB card. You'll get the specs. of CD quality, but it won't be as good. You would have to spend thousands of dollars on analog to digital equipment (I have) to be able to get that type of quality, because the A/D converters on a consumer soundcard aren't that great.
That being said,
Get Soundforge. It is better then anything that comes OEM from MS. Basically any mic will do, preferably one that came with a modem or something, because I have found that they are less likely to have background noise. There is a recording option in SF and you can use the Line-In balance on your windows volume control to set the mics bias (i don't think that is the right word, I'm getting old). Have her sing a little into the mic (which should be no closer then 6" while you set the bias so as to make sure that you set the level low enough that she doesn't clip. Then record her voice making sure that you are recording in stereo. You will probably want her to listen to the song through earphones so that the music doesn't bleed through onto your recording of her. In SF, you will have to sync the two .wav files up, which will be tricky, but after that you can drop the files on each other and save. Then burn to CD, and your done. If you have any questions, just PM me.