Amid hoopla that would make a political convention planner blush, Microsoft has unveiled version 3.0 of its Windows software, intended to bring to IBM and compatible personal computers the ease of use that has made the Apple Macintosh famous.

Earlier versions of Windows were only partially successful in making PCs easy to use. But they did, gradually, attract interest from other software houses. As a result, there is now enough business software designed specifically to run under Windows that you can actually get some work done using it.

The new version was rolled out by Microsoft's 34-year-old chairman, Bill Gates, at a press conference and MTV-style video show in New York, beamed by satellite to similar gatherings in seven other cities. The theme, repeated often by the boyish Gates, was that Windows 3.0 is "cool."

If he means that Windows 3.0 is now a much more appealing program, with better graphics, better use of color and a much-improved method of file management and computer housekeeping, it is cool, even charming. Every file now has an accompanying icon, and you can, at last, move or copy a file by dragging its icon across the screen. It has an appealing price tag, too: $149 list.

Windows now approaches the Macintosh operating system for ease of use. Like earlier versions, it permits several programs to be active, or at least loaded, at once in separate "windows" on your computer's screen. Since PCs generally cost hundreds and, in some cases, thousands less than Macintoshes of comparable capacity, Windows could be a major blow to the Mac. Apple, not surprisingly, is rushing a low-priced Mac to market.

Microsoft's announcement has generated the kind of press coverage that most companies can only dream about. PC Week and InfoWorld, the major weekly newspapers of the personal-computer industry, published special supplements full of glowing reports. The Wall Street Journal ran a flattering lead story on Gates and Windows.

Perhaps more importantly, such major PC manufacturers as Zenith, AT&T, Epson, Tandy and NEC said they would include a copy of Windows with their PCs. That is a major boost, sure to encourage software houses thinking of developing programs for Windows.

Windows will run standard PC programs, but doing that sacrifices one of its advantages. Windows programs all look alike, with similar screens, menus and commands. If you are comfortable using Windows, you have a head start in learning any program designed for it. This "common interface across applications" is a major attraction to businesses trying to standardize their PC software and cut their training costs.

As always, though, there are drawbacks. Windows is a "graphical" environment, which is how it can display all those pretty icons. Standard PC programs, in contrast, are "text-based," meaning they display only a limited set of letters, numbers and symbols that are, in effect, built into the computer. Graphical software is much more flexible, which makes it indispensable for such uses as desktop publishing and computer-aided design. But it puts much greater demands on your computer's processor, since it has to draw the screen from scratch, dot-by-dot.

As a result, graphical programs run more slowly than does comparable text-based software. Microsoft Word, for instance, runs quickly on a typical 80286, or AT-class, PC. Microsoft Word for Windows is a slug by comparison. Thus to get the ease of use of Windows and the software developed for it, you must sacrifice performance.

You can partially overcome this by upgrading your hardware. Windows is hopeless on standard PCs and XTs. It does better on AT-class or 80286 machines running at 10 or 12 megahertz. Gates insisted in his presentation that Windows is quite nimble on machines with as little as one megabyte of memory, but tests on a 1-megabyte, 12-megahertz 80286 system were not encouraging. With more than one program loaded, switching back and forth involved seemingly endless disk-thrashing as Windows swapped code in and out of memory.

Windows does better on machines with lots of what is called "extended" memory. It does nothing with the "expanded" memory now widely used by standard PC applications. So you might have to add to or reconfigure your memory. You are likely to want a faster machine, preferably a full 80386 or its less powerful, less expensive cousin, the 80386SX.

Windows is a hot product, easy and even fun to use, but if you're running Lotus 1-2-3 or WordPerfect or some other standard application on your present machine and you're satisfied, there's no reason to switch to Windows. There are tens of millions of computers that don't have the horsepower for Windows, but can handle text-based programs with ease. More such machines, particularly laptops, are being made every day.

Software for these computers will continue to be developed. So will software for Windows. The competition will improve the products and their prices. Take your time.

Brit Hume is a contributor to the Washington Post Writers Group. He is chief ABC News White House correspondent and the founding editor of a computer newsletter.