Get good speakers for your computer. Though it wasn't always the case, modern computer speakers have closed the gap on conventional music system speakers in terms of power, and they certainly compete well in regards to clarity. If you wish to boost the quality of your computer's sound further, upgrading a sound card is fairly simple.
Search various online stores such as iTunes, Napster and Amazon to build up a library of music. You may wish to build up your music collection from the Internet only, and ultimately replace your records, tapes and CDs. The major online music stores have pretty much every famous song recorded of the past 20 years and beyond. Beatles fans, however, still await the chance to legally download their music. Downloaded music can be used on portable devices such as iPods, mp3 players and mobile phones, and information about your favorite artists is easy to find.
Acquire a microphone and the appropriate lead, which you can use to plug in, for instance, a keyboard. You can make your own music, even with a simple Windows program such as Sound Recorder. You can convert music to mp3s with free shareware mp3 programs, and use free programs to edit your music and add effects. You can also put your old recordings from a tape deck onto your computer if you want to give them a modern edit. A good modern computer can be used as your own personal recording studio, and you can listen to your results through the same headphones as you would a conventional CD player.