The engineers at NASA's Johnson Space Center in Houston are responsible for making sure all astronauts and flight engineers are trained before they go to work miles above the Earth's surface. This means writing training software that accurately simulates the in-flight work environment. But the Johnson Center had a problem. While its programmers prefer to work on Unix terminals, the government requires them to use Windows apps for E-mail and other forms of communication.

About a year ago, Patrick McCartney, a Johnson Center project manager, created a Linux desktop environment that could also run government-mandated Microsoft apps. This let his team of 30 engineers continue to program in a Unixlike environment and create Word documents and Outlook E-mail all on the same PC. This mixed-use scenario is slowly taking hold, encouraged by a growing number of applications for running Linux on PC desktops.

"As PCs have become more powerful, it's easier to run Linux on the desktop and add the Windows applications and use a single machine for everything," McCartney says.

The Johnson Center's IT team installed CrossOver Office from CodeWeavers Inc. on McCartney's PCs to give the engineers access to a variety of open-source and Microsoft Office apps. CodeWeavers in mid-December introduced CrossOver Office Server Edition, a version of the product that gives workers access to open-source and Microsoft apps without having to install CrossOver Office on each PC. Server Edition is priced at $1,195 for the server software and an additional $1,185 for a 25-concurrent-user license.

One drawback to CodeWeavers' model is that the Johnson Center has to pay to license Microsoft apps, in addition to paying for CrossOver Office. But McCartney says he's still been able to save about $10,000 in the past year by getting rid of his programmers' old Unix terminals. The Johnson Center has also been able to replace a $1.6 million SGI Inc. mainframe server with a cluster of 12 PCs running Red Hat Linux for developing simulation software. The PCs were a $25,000 investment, less than half the cost of annual maintenance on the SGI server.

Better Linux desktop models exist for companies not required to use Windows. Tipic Inc. last week said it's writing a version of its instant-messaging platform to run on Linux and Unix in addition to Windows. And Ximian Inc. offers an open-source desktop starting at $30 per license with productivity apps such as E-mail and calendaring. App support for Linux on the desktop is critical to its success, Aberdeen Group research director Bill Claybrook says. "It's a less-expensive alternative for the desktop, assuming all the applications are there."