The first question you need to ask yourself is why you need a computer and for what purpose you will use it:
* Surfing the Internet
* Sending and receiving e-mail
* Word Processing
* Spreadsheet and Money management
* Listening and recording music
* Storing and manipulating images
* Playing games
When you are certain that you really need a computer then you need to consider what computer to purchase.
The most common type of computer is the PC. Fewer and fewer people these days use Macintoshes and while Apple still makes them they are used primarily for graphics work at the high end multimedia level.
For home or office use you may be far better purchasing a desktop PC with pre-installed software. And PC prices are on the way down.
Of course notebook computers are really great if you want to take advantage of the portability that they offer, although you really need to weigh this against the cost -- as laptops are still much more expensive than your average PC with the same functionality.
You need to determine what capabilities you want your computer to have