I recommend sticking to your basic design guns. Ask yourself the questions you normally would in the design process: What point am I trying to get across, and how do I do it efficiently?
Monitors are generally measured in terms of visible screen area in inches, at least when it comes to buying and selling them. However, that is only part of the equation.
Different computers can display more than others on that screen depending on what kind of video card and how much video RAM there is. This question is referring to that resolution, measured in how many pixels wide the display is. The old standard PC monitor was 640-by-480 at 72 pixels (or dots) per inch. That's not much room to work with, but most laptops and 14-inch monitors still aren't going to give you any more space than that.
However, more people now have monitors that display more on the screen. Resolutions of 800-by-600 and 1024-by-768 monitors are far from uncommon at this point.
So, it all comes back to the issue of audience. For the most part, you're not really going to lose anyone if you design your site with a larger screen in mind. On a smaller screen, your site just won't look quite the way you envisioned.
Of course there is the new issue of WebTV. WebTV bucks current trends by constricting viewable space even further. According to the specs listed on its Web site: "The WebTV screen is 420 pixels high by 560 pixels wide. The height of a Web page displayed on the WebTV set-top box is 378 pixels with a fixed width of 544 pixels and no horizontal scrolling. Design, or redesign, your Web pages to fit within the 544 horizontal pixel limit."
You can find more on that at the WebTV site's design spec page.
There's still another issue to consider: Absolute placement of HTML objects. As Microsoft and Netscape unveil their new browsers, developers will be able to specify an exact pixel location on the monitor where pictures and text will appear. Of course this has been possible in print since Gutenberg, but the Web has been a little slow to make this possible.
Sounds great, huh? Well, here's the hitch. If you specify for an element to appear at a coordinate that doesn't exist on some monitors, problems will arise and people won't get the information you're trying to give them. Oops.
The solution: Develop different versions of your site for different monitors, or use this feature judiciously.