On TV and in the movies, we see a lot of portable computers being used in homes and offices. Does that mean that's the trend? Is that what you should get?
Portable computers cost more, so unless you really have the need for one, you get a lot more computers for your money with a regular desktop PC. The main thing is portability. If you need a portable computer, get a laptop. ("Laptop," "portable," and "notebook" all refer to the same thing, by the way). Otherwise, a desktop computer is a better buy, and better ergonomically.
The Price Difference
You might wonder why laptops cost more than desktop computers with comparable features and power. That is largely because it is more expensive to manufacture laptops and their parts. For portable computer components, factors such as compactness, the amount of heat they generate, their weight, and power consumption are more important than they are for desktops. Those factors add to their manufacturing costs.
While laptops are certainly compact, a desktop computer with a flat panel monitor can take up almost as little space. While called a "desktop" computer, the computer itself is most often kept on the floor. That leaves just the monitor, keyboard and mouse on the desk, which is really very similar in footprint to a notebook computer.
A great way to further reduce the space taken up on the desktop computer is get a keyboard drawer to hold the keyboard and mouse. That way, they slide out of the way under the top of the desk when they aren't needed.
Be Mindful of Ergonomics
Ergonomics is the science of designing and arranging things so that people can interact with them more comfortably and safely. The basic ergonomic principals for computer use tell us that, 1) the keyboard should be as close to your lap level as possible (assuming you touch-type), 2) the monitor should be about arm's length in front of you, and 3) the top of the monitor should be at about your eye level. Try achieving that with a laptop computer! Two words: im-possible.
It is obvious then, that a desktop computer is much better ergonomically than a laptop is. For prolonged use, especially, you're much better off with a desktop computer.
And Don't Forget Usability
Another aspect of ergonomics is usability. Because of size constraints, laptops also are lower on the usability scale than desktop PCs are. For one thing, laptop keyboards lack the separate groupings of the different sets of keys with space between them. For another, there are fewer keys on a laptop's keyboard, so some of them have to perform double duty. On a standard keyboard, you don't have to deal with that.
Computer monitors -- the bulky ones, anyway -- can be set at different resolutions. In other words, you can change the fineness of the image on the screen. The range is typically 640x480 -- that is 640 pixel across and 480 pixels up and down -- to 800x600, 1024x768, or even higher. At 640x480, the icons and such appear quite large; at 1024x768, they are substantially smaller. The most common resolutions today for desktop computers are 800x600 and 1024x768.
Something They Don't Tell You
Laptop displays, on the other hand, have a fixed, or native, resolution. You can change the setting, but then the images and text don't look good. While people tend to think that bigger numbers are better, a higher screen resolution may not work as well for you. It may make everything too small to see comfortably.
Remember, the laptop's screen is smaller than a desktop's. While a typical desktop computer screen is 17" or so a laptop's is usually in the range of 12" to 15." That is a big difference. Make sure you can see everything clearly before choosing a high-resolution laptop.