Computer geek said..
If you need portability, you want a laptop. If you like to write papers or do your work in a library, at the beach, or while sipping margaritas on your porch on a warm summer day, think about getting a laptop. With wireless Internet available in more places, laptops are handier and handier. If you travel a lot and do work on airplanes, get a laptop. If you don’t have a lot of desk space, get a laptop. If you need a very high-powered workstation, don’t want to pay a premium for your system, or play a lot of 3D games, consider a desktop instead.
Laptops are always a step behind desktop computers in speed due to the need to fit everything into such a small case while keeping heat levels and power consumption to a minimum. If you like the idea of upgrading your computer piece by piece, get a desktop system. Laptops are much less upgradeable than desktop systems. Now that prices are so reasonable for low-end equipment, you may want to consider a combination of desktops and laptops for your home.