But there are some caveats that indicate the dominance isn't quite as strong as TurboLinux announced.
TurboLinux's retail sales of its Linux version accounted for 24 percent of the sales during the week, the company said. In comparison, Microsoft's Windows 98--including upgrades--amounted to 22 percent, according to numbers from the Japanese market analysis firm of Business Computer News.
However, including academic versions of Windows 98, that number rises to about 30 percent, about 6 percent ahead of TurboLinux.
In addition, International Data Corporation analyst Dan Kusnetzky warned that looking at the first week that a new software product goes on the market isn't necessarily a good long-term measurement.
"There is almost always a peak very early on, and then it slows down," he said. "You can have a high point that isn't necessarily followed through with shipments after that."
TurboLinux is the dominant version of Linux in Japan, IDC has said. TurboLinux is in the midst of a push to increase its sales in North America, recently dropping its older name Pacific HiTech to reflect its wider geographical aspirations. Red Hat currently makes the most popular version of Linux in the U.S.
A TurboLinux spokesperson said the company hasn't yet been able to get sales data for the period of time after the announcement of the new version of the software, TurboLinux J 4.0.
Linux, an open-source clone of Unix originally crafted by Finnish student Linus Torvalds, has been gaining market share rapidly, IDC has said. While its stronghold is in server computers, many developers are working to create software that will make Linux easier to use on desktop computers used by novices--the market at which Windows 98 is targeted.
However, many popular software programs still aren't available for Linux, such as Quicken financial software or Microsoft Office.