Sound & Graphics
At one time quality sound and video components added hundreds of dollars to the price of a PC. Now, people can expect to find satisfactory performance from the components that come standard on the motherboards. Here's an outline of the minimum quality you should accept and what to look for if you want greater performance.
     
Video Cards
Also known as graphics cards, these components are responsible for displaying 2D and 3D images on your monitor. 2D graphics are the regular pictures and images that appear on your screen while 3D graphics are mostly used in games and imaging. Most computer systems come with video cards that produce acceptable 2D results but there are reasons to upgrade.

Unless you have at least 32 MB of video RAM you can experience some image stuttering on your monitor when performing tasks like moving windows around and scrolling through text. This can become even more of an issue if you have a 19" or larger monitor. Most people with these monitors use a resolution greater than the 800x600 and maximum possible resolution is a function of the amount of memory a graphics card has. Therefore if you are getting a 19" or larger monitor you should have 64 MB of RAM.

Game designers continue to create more and more elaborate games, which require a yearly upgrade of the video card for the most devoted gamers. If you want to ensure that your setup has some longevity for playing the latest games you will want a 3D card with 128 MB of RAM or more.

The two major names in high-performance video cards are ATI and NVIDIA. Their cards all provide excellent performance with 2D graphic intensive programs as well as 3D games but as you move up their product lines you'll experience greater speed and more brilliant graphics.

Here's an overview of their product lines and whom they are geared towards.

  Entry Level Mid Level High End
ATI Radeon 9200 Radeon 9600/9700 Radeon 9800/X800
NVIDIA GeForce FX 5200 GeForce FX 5700/ FX 5900 GeForce FX5950/6800
     
Sound Cards
The sound card is either attached or built in to your PC's motherboard. Its job is to control the quality of audio in and out of the computer. There should be input jacks for speakers, headphones, microphone and line-in for audio components like a tape deck. Beyond that, most sound cards that come with a new computer system will offer a suitable level of performance for average use.

If your audio requirements are more advanced or you play a lot of games, you should consider a PCI sound card with a wider range of features. At the top-end there are cards with Dolby Digital 5.1 surround sound and S/PDIF digital output, the audio format that is used in many home theatres.

Positional or 3D audio is offered by higher-end sound cards and can make games and music come alive. For example, when an enemy is about to attack, you can detect which direction he's coming from by the sound of his footsteps. Advanced sound cards also support midi devices and come bundled with better audio software (encoders, editors, mixers, etc.).
     
Speakers
If you plan to take advantage of any of your PC's multimedia features, you'll want to invest in a decent set of speakers. At the very least you should make sure that they are powered by an external source. Speakers powered by the sound card are incapable of producing rich and dynamic audio. Gamers and serious audiophiles will want at least 30 Watts of power with a separate subwoofer for ample bass reproduction.

The more money you spend on your speakers the closer you can come to approximating the dynamic audio of a home theatre. A basic pair of speakers will suffice if you're using the system mostly for productivity applications like word processing and Web surfing. If you want to enjoy music, consider a three-piece system that includes a subwoofer for better bass response. For games, a five-speaker surround sound system is a good investment. And if you're getting a DVD-equipped system and want the PC-theater experience, you could go all out for a 7.1-channel surround sound system, though that's far more a luxury than a necessity.

  Number of Speakers
Entry Level 2.1 - Left, right and a separate subwoofer
Mid Level 4.1/ (5.1)- Two in front, two in back, (one in center) and a separate subwoofer.
High End 7.1- Two in front, two in side, two in back, one in center and a separate subwoofer.
     
CD-ROM/CD-R/DVD/Data Storage
While the humble CD-ROM drive continues to perform its duties well, a number of other devices have arrived over the last few years that build on its strengths. CD-R/CD-RW drives can read CD-ROMs as well as write data to discs, providing the user with a huge amount of personal and portable storage space.

DVD drives are faster while storing many times more data than CD-ROMs and are not much more expensive. DVD drives can also play CD-ROM discs. The most popular media available in DVD are movies. Some software is available on DVD but the vast majority is still published on CD-ROM.

In the current marketplace, Combo drives (DVD & CD-R/CD-RW) and DVD Dual drives are becoming standard equipment on many mid-range and higher PC's. Since the price difference between a CD-R/CD-RW and a Combo drive is slim, your best bet is to go with a Combo drive.

Note that CD and DVD drives come with speed ratings expressed as the number of times faster they transfer data than standard audio CDs or video DVDs. This rating becomes a concern primarily if you're writing large amounts of material to your optical drive: While a 4x (write) CD-RW drive takes around 20 minutes to create a disc full of music, a 12x (write) CD-RW drive can accomplish the same task in a third the time.