What's the optimal size of a personal computer? That's a question PC makers wrestle with all the time in designing new models, and it's a question every PC buyer should consider as well.

The trend is clear: Small. For the most part, stationary desktop PCs as well as portable PCs have gotten smaller over time, one exception being monitors, which have increased in size.

When taken to an extreme today, you wind up with a handheld computer, also called a palmtop computer. Taken to an extreme in the future, we'll likely have fully functional, voice-activated, talking computers embedded in our wristwatches, clothing, and eyeglasses.

For now, the more mundane and more practical issue is how small should you go when buying a new computer device for work, play, or both.

Netbooks

A relatively new category of computer devices, netbooks, adds a new option. Also called mininotebooks or subnotebooks, these are the smallest computers today that have keyboards that you can type into with both hands for quick data entry. Unlike notebook PCs, they don't typically include a CD-ROM/DVD drive.

The name "netbook" came into use because these devices are ideally suited for using Web applications. Instead of running programs that reside on your computer's own hard drive, you run programs over the Internet that reside on server computers elsewhere. Google Docs (docs.google.com) is the best known.

Netbooks as a product category are only about two years old, emerging in late 2007, though some contend that netbooks first came into existence in 1999 with the Psion netBook, a device that never caught on. Today's netbooks have caught on, comprising nearly one-fourth of all portable PCs sold, according the latest report by the market research firm DisplaySearch. Compared with a year ago, netbook sales revenue grew a whopping 264 percent.

The attraction of netbooks is clear. Compared with other laptop computers, they're lighter, run longer on batter power, and cost less. The main negatives are the flip side of the positives. The smaller keyboards are more difficult to type on and the smaller screens are more difficult to read.

Some analysts have speculated that the netbook boom will end when the economy recovers, removing some of the attraction of their low price, which ranges from about $250 to $500. But market research firm iSuppli Corp. predicts that their popularity will continue to rise, with netbook shipments projected to quadruple over the next four years.

Top netbook brands, according to the latest testing by Consumer Reports, PC World magazine, and the online sites CNET and NetbookReviews.com, include those by Acer, Asus, Gateway, HP, and Toshiba.

I tested out netbooks by Acer and Gateway. The Gateway LT3103u is typical of larger netbooks, while the Acer Aspire One AOD250-1042 is typical of smaller ones. The Gateway has an 11.6-inch screen, 2 gigabytes of memory, and a 250-gigabyte hard drive, the Acer a 10.1-inch screen, 1 gigabyte of memory, and a 160-gigabyte hard drive.

I liked the Gateway better, but I'm a dyed-in-the-wool desktop PC aficionado, preferring faster typing and easier viewing over the convenience of smaller size. The Gateway is available from