You could also use Windows Media Player for ripping CD's. Easy as hell, and can produce mp3 files.
For mp3s, I generally use either 128 or 192 kbps.
What is good enough depends on both you and the music you listen to. If you're an absolute listener you'll need a higher bitrate. If you've got "normal" ears you can do with a lower one. If you listen to slow, calm music, a lower bitrate will do. If the music you listen to is fast and dynamic you need a higher one.
There's no way of really knowing what will be enough for you, besides testing. I'd recommend to start at 128kbps and move up from there (testing can be done at your PC)
