McGyver could do just about anything with his Swiss Army knife. The laptop is the digital equivalent of that versatile tool, and today they hardly cost much more.

Want to watch a movie? Pop in a DVD. Want to listen to music? Try a CD, or play your MP3 collection, or stream music from the Internet. Want to watch television? Stream shows from the Web, or get a digital tuner and get local broadcasts for free. Got a digital camera? Use a laptop to preview your pictures. You can even make phone calls, with an app called Skype.

Best of all, this miracle product is suddenly cheap! You can find hundreds of choices that sell for less than $400. So how do you decide which is best for your needs? Here are some tips that will help you pick, even if you don’t know a pixel from a port.

SLIDESHOW: Super-cheap laptops

Netbook vs. Laptop: A netbook is cute new term for "small laptop." They typically have a 10-inch or smaller screen and weigh 3 pounds or less. With their small size, there isn’t room for a DVD drive, so you’ll have to get an external one as an accessory. On the other hand, Wi-Fi for networking and Internet access is generally included.

A netbook is a great choice for someone who travels, or someone older who wants a lightweight computer. Asus pioneered the field, with products like the neat $375 Eee PC 1000HE.

CPU: This cyberbabble acronym stands for central processing unit, which simply means the brains of the device. You’ll sometimes see it referred to as simply "the processor." Like the engine of a car, processors vary in power, which in turn means how much work they can do and how quickly they can do it.

If you’re just writing e-mails, surfing the Web, writing papers and so on, any processor from Intel or AMD will do just fine, be it a Celeron like in the Toshiba L455 or something else. If you want to do more, like some fancy photo or video editing, you’ll want a "dual-core" processor, which simply means it has two brains in one chip.

Memory: It really makes a difference; without enough, the laptop will run noticeably slower. 2GB is generally a good place to start. Note that most netbooks are limited to 1GB of memory, especially those that come with Microsoft Windows XP Home. Choose a different version of Windows if available and upgrade to 2GB.

Screen Size: Some mini-laptops have screens that are 10 inches (diagonal) or smaller. This can be a bit cramped for office applications, but is still plenty for email and Web surfing and other tasks (provided you sit close enough and your eyesight is good or you have good glasses).

One added benefit of a 10-inch screen, like the one on the Lenovo IdeaPad S10: You can use it on an airplane tray table in coach, even if the seat in front of you is cranked all the way back.

Memory Card Slots: These are often called "memory readers" and can be very handy. They let you take the memory card out of your camera or MP3 player and transfer files directly to the computer. It’s much faster and easier than connecting the two devices with a cable. Some laptops only support the SD card format, which is the most commonly used card format.

If your devices uses some other form of memory card, either make the laptop can support it or plan on getting an accessory device for memory cards. Look for a multicard reader, like the one in the Acer Aspire One D250.

Batteries: The ratings specified by most laptop manufacturers are almost always too optimistic. If you need to work for long periods on battery power, it’s a good idea to buy a spare battery so that you have more power if the first one runs down.

Each battery is more or less unique to each model of laptop, so in general you’ll have to buy the manufacturer’s battery. The HP Mini 110 packs a bigger-than-average battery, though it's somewhat bulky.