There are several different kinds of computer packages and just about any desktop computer package usually consist of memory, processor, and an operating system in the basic system. It really depends on what you will be using a computer for as to which package is right for your specific needs.
For instance, if you are a gamer, you will want one with a more than the average amount of memory as well as a good 3d graphics card. However, if you are planning on just using your desktop for checking email and surfing the internet, you will not need all the extras. You can also purchase computer packages that include printers which are great for students or even if you just like to print pictures.
If you like to download music or pictures from the internet, a desktop computer package with at least 512 mb of memory is best because the less memory you have, the slower your computer will run when you download a good bit of music or pictures. You can also purchase surround sound with your computer package as an added feature if you prefer. This is great for watching movies or listening to music.
Each manufacturing company has several different choices of desktop packages and most of these companies let you choose what you want included in your desktop computer system. You can also ask for more information about what system would be best in reference to how you will be using it. Most computer sales reps can provide more in depth info for helping you choose the best system. Keep in mind that every company offers different features in various packages, so it would be a good idea to shop around a bit before making up your mind.