The Laptop/Desktop Conundrum
Although laptops have become a lot more powerful and functional in the past few years, the basic advice remains the same. Unless you need the portability or battery power, you're generally better off with a desktop computer.
Desktop systems are cheaper than laptops. For equivalent performance you'll pay between one-third and twice as much for a laptop than you would for a desktop.
Desktop computers are usually more powerful than laptops. You can get bigger disks, faster processors, and larger screens with a desktop computer for the price.
Laptops are notoriously hard to repair and usually just about impossible to upgrade. All that stuff crammed into a laptop's case means special parts and lots of non-standard equipment. If you buy a laptop from a major manufacturer you're probably fine for as long as the company supports it. When they stop supporting it, you could find you've got a boat anchor, not a computer. If you do get a laptop, it's important to get it configured exactly as you want it when you buy it. The chances that you're going to be able to swap out your disk drive, for example, are pretty slim. Also, upgrades for laptops are generally more expensive than for desktops.
That said, laptops have some definite advantages for the non-road warriors among us. The freedom that comes with being able to take your computer to the park or library whenever you want is significant. So is the ability to keep working when the power goes out. Plus, there's the definite "cool factor" of throwing a laptop in your backpack.
Just keep in mind that you pay a price for portability must be balanced against a lot of other factors.