Is there anything new out there that’s exciting enough to make replacing your current desktop computer worthwhile? After looking around, here’s my bold and brash answer: It depends.

The hottest new desktop PC technology is dual-core processors, with both Intel and Advanced Micro Devices (AMD) now selling these chips to PC makers. These central processing units (CPUs) are the hearts of computers. They’re designed to speed up “multithreaded” software programs and multiple individual programs that operate concurrently.

The problem is, there are few mainstream multithreaded programs on the market. I use Photoshop Creative Suite 2 (CS2) with a dual-core processor desktop system and have noticed a significant performance difference. But the overall speed increase with other programs is modest at best. PC World and PC Magazine also experienced these results in their tests.

Another promising desktop technology from both Intel and AMD is 64-bit processors, as opposed to the standard 32-bit processors. But they also face the problem of today’s mainstream software not yet being able to take advantage of their speed-increasing potential.

As usual, it takes software companies time to catch up to the advances in hardware technology.

For most people, having the latest technology is less important than reliability. It doesn’t matter that you finish a computing task a couple of seconds faster if your computer is giving you problems that take hours to solve.

According to the latest Consumer Reports user survey, the most reliable desktop computer makers are Apple, Sony, and Dell, though the difference between them and other top brands is relatively small.

When making buying decisions, one tactic is to look at market share numbers. The company that sells the most PCs isn’t necessarily the one you should buy from, but the collective intelligence of the computer buying public can often point you in the right direction.

I asked Joy Shao, an analyst at market research firm Gartner, Inc., to pull together some numbers. The top three PC makers in terms of U.S. private (home) sales and professional (business, educational, nonprofit, and government) sales are, respectively, Dell, Hewlett-Packard (HP), and Gateway. (Apple was fourth, but it bettered Gateway for professional sales.)

Compared with last year’s figures, Dell’s sales are up 6.7 percent, HP’s have increased 2.6 percent, Gateway’s have improved 15.1 percent, and Apple’s have risen 38.6 percent. According to published figures from IDC, another market research firm, HP’s sales figures grew slightly faster than Dell’s in the latest quarter. This decreased the gap between the world’s two largest PC makers, with Dell having 18 percent of the worldwide market and HP 16 percent.

When deciding which computer to buy, it can also be smart to weigh the experiences of colleagues, friends, and family in with your own. An accumulation of impressions can be the deciding factor.

HP has always struck me as being a “good guy” company, providing a range of solid, popularly priced products from desktops and printers to projectors and digital cameras through large retail outlets. Gateway’s folksy image is backed by its long history of providing quality, high-performance technology through mail-order sales. Other people swear by the generic “white box” PCs available from their trusted local computer store.

One continuing trend is the move from desktop to notebook computers for in-office or in-home use, a trend I don’t completely understand. (However, I can see the utility of having a notebook if you frequently—or even occasionally—need to compute while on the road.)

Notebooks remain more expensive, slower, and less ergonomic than desktops. With a flat-panel monitor, a desktop takes up only slightly more space than a notebook. Computing while slouching on a sofa with my notebook just doesn’t appeal to me or my back.

Some consultants advise you to replace your desktop every 2 or 3 years, but most people keep them longer—often 4 or 5 years. The key question to ask yourself is whether or not you’re still able to do what you want to do with your current system.

Prices today are as low as they’ve ever been. The least expensive system at CompUSA, for instance, sells for $399.98 with monitor after rebate. The most popular systems there and elsewhere are in the $700 to $1,000 range.

One wild card is Microsoft. Some people wait to replace their systems until Microsoft comes out with a new operating system or it releases the first service pack of bug fixes. Windows Vista, the next version of Windows, isn’t due out until late next year, and this projected date may be pushed back as it approaches.