This article will walk you through the choices you need to make and provide guidance for what to choose.
In order to answer this question properly, you need to decide what type of user you are and what special needs you may have. Additionally, you need to determine how much you want to spend and whether you would consider buying a used or refurbished computer.
As a general rule, my opinion is that one should get the most computer that they can afford without getting the actual top of the line.
Computer technology changes rapidly and today's super fast and capable computer rapidly becomes outdated. Unless you are interested in swapping your computer frequently, getting a very capable current computer should hold you for at least a few years.
The very top of the line computer demands a premium in price that is generally not worth it and one level below has at least 95% of the capability of the top.
If your budget doesn't allow for this solution, you need to be aware of the tradeoffs in various choices that you will have to make.
Computer type selection
You should first decide if you want a laptop or desktop computer. I've discussed the issues at length in my article entitled Desktop or Laptop? The main question is if you have the need to be mobile even though your computer will cost more and possibly have less capability.
Depending on one's finances, you may opt for used computer or for a blowout special. Great savings can be achieved by taking this route.
However, used computers present support challenges and the risk of early breakdown. Low priced bargain computers may be limited in ultimate capability and need to be carefully evaluated. I hope to discuss these options in greater detail in a future article.
Heavy duty 3D gaming is a whole new world and generally pushes current computer technology to the limits with top of the line powerful and expensive units and is out of the scope of this article.
If money is not a pressing issue, single core computers should not be purchased. Dual core processors are more powerful and, for most users, any dual core processor based computer should suffice for standard activities such as word processing, email, browsing the web, watching DVD's, doing one's finances and the vast majority of other tasks.
If you need to do heavy database querying, complicated mathematical computations and number crunching or heavy encryption, you should get one of the higher end processors.
2. Operating system
Assuming a Windows PC, the choices are between XP and Vista. Vista Service Pack 1 (a set of fixes to the known problems of the operating system) has not yet been officially released and the first service pack usually makes a big difference. My opinion is that if there is a choice, Vista should be avoided until SP1 is officially released.
If you are very familiar with XP and don't want to struggle with learning a new operating system or you have a program that is not supported on Vista yet, XP can do everything you need and you can request it worry free if your vendor allows for this option.
If you select Vista, at a minimum you should not get Vista Home Basic but rather select Vista Home Premium. For maximum OS power, Vista Ultimate should be chosen. The detailed options for Vista are outlined in my article Which Vista should I Use?
A 17 inch monitor is probably the smallest that you should settle for. You can select larger ones if you so desire. Some monitors come with built in speakers if that suits your needs. If you want your computer to double as an entertainment center, you should consider purchasing a high definition or plasma monitor. Dell has an excellent summary of their choices here
The most crucial factor in terms of computer performance is the amount of memory. When you buy computer memory, a minimum of a gigabyte of high speed memory should be selected to support today's demanding operating systems and programs. 2 gigabytes would be even better.
If one is engaged in heavy duty graphics such as CAD (Computer Aided Design) or 3D gaming, or if one is doing heavy database access or number crunching, even more memory should be added.
5. Hard Drive Size
Major manufacturers are offering drives with 250 Gigabytes of storage on their lowest end computers. This should be more than enough for most users.
6. CD and DVD burner
Drives that read and write to CDs and DVDs are cheap and you should specify read and write for both. Don't accept CD read/write and DVD read only.
Blue Ray and HD DVD disks can hold up to 50 gigabytes but the drives needed to use them are much more expensive than standard DVD drives. Standard DVD drives will run around $50 while Blue Ray will cost around $600.
7. Video card
The type of card that you get depends on the type of activities that you are planning;
1. Basic user - word processing, internet browsing, email and DVD movies
The basic level card will suffice for this. It should have at least 128MB. 2 representative cards are the Nvidia 7300GT and ATI 1300XT.
2. Vista Aero User or light gaming, rich media, and general entertainment
This capability requires mid level graphics power and a card with at least 256 MB of its own internal memory should be purchased. A sample card would be ATI HD2600XT
3. Edit and view photographs in brilliant color
A mid level card should be used for this. One example is the NVidia 8600GT, All cards from this level and up should have at least 256 MB.
4. Playback HD quality content
The card should have HDMI outputs to attach to external displays. 2 possibilities are Nvidia 8600gt or ATI HD2600XT.
5. 3D accelerated games in high definition player, CAD (Computer Aided Design), video editing or high level graphic design
3D gaming makes the greatest demands on the computer's video systems and the sky is the limit here. In general, the highest level card that your system will accept will provide the most satisfying experience.
The detailed options for each of these levels of activity are described in my article Video Cards Demystified.
8. Sound and Speakers
The standard sound card offered by most manufacturers is fine. If you have special requirements, the major dealers describe the advantages of the various upgrade offerings.
Speakers project the sound of your computer. Better speakers provide subwoofers and different levels of surround sound.
9. Keyboard and mouse
Connected or wireless versions are offered. Be sure to get an optical mouse. They are much more reliable than a trackball mouse.
10. Media reader
These are usually listed as 15 in 1 or 13 in 1 card or media reader. This device allows you to directly get data off of a number of devices such as digital cameras, personal digital assistants (PDAs) and others.
If you want to send or receive faxes or connect to the internet via a phone line where high speed internet may not be available, you will need a modem.
12. Wireless network
If you plan to connect to a wireless network, you will need a wireless network card in your computer. Standard network cards are built in.
Best of luck with your purchase.