•Other speed boosters. Separate graphics chips, sometimes called "discrete graphics," can vastly improve a PC's performance by crunching images separately, instead of relying on the main processor to do it. Discrete graphics are a must-have for video games, says Brian Bruning, director of handheld content for graphics chipmaker Nvidia. But they can also speed up tasks such as dragging a photo across the screen, he says.

Another way to increase performance is to add memory, sometimes called random access memory, or RAM, says John New, a product manager at Dell. Memory is where a PC temporarily stores information while it processes it. Sufficient memory is the difference between "a computer that keeps grinding and grinding and one that feels really smooth," Reynolds says. Microsoft's Vista operating system alone requires 512 megabytes (MB) of memory.

Memory also has the benefit of being relatively inexpensive. Look for computers with at least 2 gigabytes (GB), Knupffer says.

•Storage. Thanks to the soaring popularity of digital music, photos and video, it's surprisingly easy to fill even a large computer's hard drive. Anyone with a digital camera should have at least 300 GB of storage on their primary computer, says IDC's Shim.

And don't forget a way to back it up. "It isn't obvious, but the $1,200 (someone spends on a PC) can quickly be exceeded by the value of the digital music and movie library they store on it," says Dell's New. Simple external hard drives, which plug into a computer's universal serial b