A. If you think that hard disk-based portable audio players, such as the Apple iPod or Creative Nomad, are expensive, consider this: These players can store your entire music collection in a single, portable location, which is perfect for long trips and even the daily commute. If you do a lot of driving, you can connect such a device to your car stereo using an inexpensive (about $20) cassette adapter and always have access to your CD collection, no matter where you are. Just remember to keep your eyes on the road and preprogram a playlist before you leave the driveway.