The best Video Card to buy will depend on what you will require from your PC. If you will be running business applications and other 'visually' low performance applications, then a reasonably low specification, low price Video Card will suffice.
However, if you are building a PC with the intention of playing the latest 3D games, a Video Card of a much higher spec. will be necessary to handle the very demanding output from such games.
A video card may have any number of connectors depending on it's built-in features, like TV-Out/In, S-Video or Digital Video, but be sure to choose a Video Card which has a suitable connector (or can be adapted) for the type of Monitor you intend to use (see next page.)
Today's Video Cards are of two basic types: AGP and PCI-Express, with the latter offering the higher performance in some cases.
Reputable Video Card Brands: nVidia, ATI, Matrox, Asus, MSI, Leadtek, XFX
Be aware that some motherboards feature built-in Video and Sound cards. In this case, it will not be necessary to purchase an additional Video/Sound card.
Here again, as with the Video Card, your choice of Sound Card will be dependant on your requirements. Business applications will have very little benefit of a sound card, whereas games can sometimes seem unplayable without one. A Sound Card with a 'stereo' output is fairly standard, but many now come with all manner of extra sound options to enhance your PC's audio output.
If you buy a sound card for your PC, you will need some speakers to go with it. A pair of 'Stereo' speakers is standard, but it is possible, with the right sound card and speaker package, to create surround sound such as you might hear in a cinema.
Reputable Sound Card Brands: Creative Sound Blaster, M-Audio, Terratec, Voyetra