The Linux-based servers at Austin Energy run applications such as Exchange 2003 for e-mail, network management and security, as well as the utility's mission-critical supervisory control and data acquisition (SCADA) software.

The SCADA servers are blocked off from the Internet for security reasons, which made Red Hat Linux unsuitable, according to McDonald, who also tested that operating system.

"My Red Hat boxes were always running home to mama, always pinging the Red Hat Web site to download patches and updates," he said.

But despite favorable reviews from McDonald and some other corporate users, Mandriva will have a tough time challenging Red Hat and Novell in the Linux server market, said Gordon Haff, an analyst at Illuminata Inc. in Nashua, N.H.

"For supported Linux enterprise distributions in North America, Red Hat -- with a smattering of Novell -- is the only game in town," Haff said. "It's really hard to see what would suddenly cause [Mandriva] to become a success in North America."