DIY: Notebook buying

Sometimes referred to as the CPU, or central processing unit, the processor is the brains of the computer. It's the most important chip in a notebook, and it has power-management features that extend battery life. Notebooks use a variety of processor types depending on their focus. We've explained each in the chart below:

PROCESSOR	NOTEBOOK TYPE	PROS AND CONS
Mobile AMD Athlon 4	Budget notebooks	Inexpensive but a bit slower than Intel Pentium chips, according to CNET Labs' tests.
AMD Althon XP-M chips	Desktop replacement, thin-and-light notebooks	Still undergoing tests. No conclusion yet.
Apple PowerPC G3	Apple iBook (budget notebook)	Long battery life and relatively inexpensive, but slower clock speeds limit performance, especially under OS X.
Apple PowerPC G4	Apple PowerBooks (performance and desktop-replacement notebooks)	Excellent performance and reasonable battery life but expensive, and clock speeds top out at 1GHz.
Mobile Intel Celeron	Budget notebooks	Extremely inexpensive, slightly slower than Intel Pentium chips.
Mobile Intel Pentium III-M	Ultraportable notebooks	Less expensive than many other processors but not as powerful. Longer battery life allows for lower system weight.
Mobile Intel Pentium 4-M	Desktop-replacement, thin-and-light notebooks	Very fast and expensive. Allows for only mediocre battery life.
Intel Pentium M	Desktop-replacement, thin-and-light, some ultraportable notebooks	Part of Intel's Centrino technology, the PM is both very fast and allows for long battery life. Very expensive.
Intel Pentium 4	Desktop-replacement notebooks	A chip intended for desktops, the Intel P4 is very fast and is less expensive than Pentium 4-M and PM chips, but it runs very hot and allows only poor battery life.
transmeta Crusoe	Ultraportable notebooks	Long battery life but very slow.

Every computer comes with a certain amount of physical memory, usually referred to as main memory or RAM (random-access memory). Computers store currently running applications and data in this area. To find out how much memory you'll need, take into account your operating system and the applications that you plan to use. A general rule of thumb: You'll need 256MB for Windows XP or Mac OS X and 128MB for all other Windows and Mac operating systems.

If you're planning to hang on to your notebook for a long time, look for a laptop with easy-to-access memory slots, as memory is typically one of the first specs you'll want to upgrade.

Unlike traditional desktop CRT (cathode-ray tube) monitors, notebooks ship with thin, liquid-crystal displays (LCDs). Notebook LCDs range in size from 12.1 inches (diagonal) to 17 inches. For comfortable viewing at the preferred Windows resolution of 1,024x768, most people like 14.1-inch or larger LCDs.

The ultraportable Fujitsu LifeBook P series (left) has one of the smallest screens -- just 10.6 inches -- in order to accommodate its feather-light, 3.1-pound weight. The giant 17-inch Apple PowerBook (right), on the other hand, has the biggest notebook screen we've ever seen.

Notebook LCDs once varied widely in brightness, colour, and sharpness, but today, you'll find much better quality across the board. Unfortunately, when it comes to LCDs, the specs reveal little about actual picture quality, so if you're picky about screens, compare some at your local dealer.