Dell planned to release on Thursday two desktops and a notebook running Ubuntu Linux, launching the highest-profile market showcase for the open-source operating system.

The XPS 410n and Dimension E520n desktops and the Inspiron E1505n notebook are scheduled to make their debut at 6 p.m. EDT on the Dell site. The consumer computers will run factory-installed Ubuntu 7.04.

The long-awaited release is a landmark for Linux in the consumer market. Until now, no computer maker with the market strength of Dell has made a similar commitment to supporting the free software.

The systems come with hardware support through Dell's normal support channels. Software support will come from a variety of dedicated Web sites and Linux forums, Dell said. Buyers can choose service upgrades from Canonical, the sponsor of Ubuntu. They include a 30-day "get started" service and a one-year basic,, or standard, service.

To help customers get more help with running Linux, Dell has created a Linux forum that offers buyers an online channel for discussing experiences and sharing information.

The Inspiron notebook includes a 15.4-inch display, 512MB of memory, an 80GB hard drive, and a CD/DVD drive that can burn CDs but not DVDs. The system is powered by an Intel Pentium Dual Core T2080 microprocessor and has built-in Wi-Fi support. Pricing starts at $599.

The Dimension and XPS desktops have nearly identical configurations. Both include Intel Core 2 Duo E4300 processors, 1GB of memory, a 250GB hard drive, and a 256MB Nvidia Geforce 7300LE graphics card. The XPS, however, includes a 19-inch display, versus a 17-inch for the Dimension, and a read/write DVD drive. The Dimension has the same drive as the Inspiron. Pricing starts at $599 for the Dimension and $849 for the XPS.