Desktop and laptop computers can provide similar performance in very different packages. When you're thinking about a new computer, it's essential to decide which type meets your specific requirements.
The most important advantages of desktop computers are related to economy and the size of the components inside and outside the case. Bigger keyboards and screens make it easier to use your computer, while the modular construction and extra space inside the box allow you (or your service technician) to repair or modify the computer more easily. On the other hand, those big cases and external devices are all heavy and bulky, so they're more difficult to move around.
Laptop computers are compact and easy to transport, but that also makes them harder to use and to service; the keyboard and screen built into a laptop are smaller than the separate units connected to a desktop computer, and less flexible when it's time to upgrade to a faster and better system.