A program can't ever really die, but it can get old.
This is a paradox millions of computer users are living with. Almost four years after the release of Windows XP and Mac OS X, they boot their machines into more senior versions of Windows or the Mac OS.
Those operating systems still fire up in the morning as they always did. But they show their age in other ways -- newer programs and gadgets can't or won't coexist with them.
The research firm IDC estimates that of the roughly 514 million paid-for copies of Windows on desktops and laptops worldwide at the end of 2004, almost 21 percent were the aging Win 95, 98 and Millennium Edition releases. Among the 19 million Mac OS desktop and laptop installations IDC surveyed, just about half were running releases predating Mac OS X.
If your machine is among that contingent and you find that it performs its assigned tasks properly, there's no problem -- for you, the software is old but not obsolete. But if you're still using your machine for the tasks it was designed for, you are likely in a small minority. Home computing these days has little in common with five years ago, and not all of these changes leave room for older systems.
Here are how the past few consumer releases of Windows and the Mac OS compare in terms of viability:
Windows 95: This nearly-decade-old operating system is swimming with several anchors around its neck, the heaviest of them being its lack of USB support. That rules out using the vast bulk of the devices -- printers, digital cameras, MP3 players, handheld organizers -- made in the past few years.
Software support for Win 95 is vanishing, too. Microsoft last released a Win 95 version of its Internet Explorer browser five years ago; AOL's software last supported Win 95 in 2001. Nor can you run the current editions of Intuit's Quicken and Microsoft Money in Win 95.
Windows 98: This version has weathered the years better than Win 95. For one thing, USB does work in Win 98, although not perfectly (for instance, most of Creative's MP3 players, Epson's printer/scanner combos and many WiFi adapters need newer Windows releases).