The CD-RWs, which cost a little more, are rewritable and can be used multiple times. There are also blank CDs made for recording music only. This carries visual data from your computer to your monitor and helps determine the quality of the picture you see. Ask, don't assume. The key name to remember is Sound Blaster, or at a minimum Sound Blaster-compatible.
Manufacturers make other specialized sound cards for different uses, such as music.
The type of monitor you have determines the size and quality of the picture you get from your system. Most systems are packaged with 56K v.90 modems that are also capable of sending and receiving faxes. There also are voice modems that can serve as a telephone answering machine. Any computer purchase must be rounded out with a decent printer. The way to go for home use is a color ink jet.