Dell has become the first systems maker to join last year's Linux pact between Microsoft and Novell covering interoperability, technical support and intellectual property rights.

The announcement adds weight to a deal that has proven highly controversial in the Linux community - including within Novell itself.

Separately, Novell's head of desktop Linux said on Friday he was leaving the company.

The new agreement comes only days after Dell confirmed it would begin offering Ubuntu Linux pre-installed on desktop systems. But Dell's extension of the alliance between Microsoft and Novell, which Microsoft has said implies that Linux contains Microsoft's intellectual property, already appears to have drained much of the goodwill Dell had fostered among Linux enthusiasts.

Under the original deal, Microsoft agreed to buy about 70,000 Linux certificates a year from Novell over a five-year period, each entitling a customer to technical support for Suse Linux Enterprise Server (SLES) from Novell. That part of the agreement in effect put Novell on Microsoft's bankroll, and is designed to encourage customers to deploy Windows and SLES side-by-side.

As part of Dell's announcement on Monday, the computer maker said it would buy some of Microsoft's Linux support certificates, but didn't specify how many. Dell will also establish a services and marketing programme designed to encourage existing Linux users who are not already Dell customers to migrate to SLES.

The effort will include the establishment of a new customer marketing team, which will run interoperability workshops, establishing proof-of-concept migration scenarios and migration services.

The controversial part of the agreement is a cross-licensing agreement which, according to Microsoft, gives Novell and its users indemnity for the Microsoft intellectual property which Microsoft claims is in any Linux distribution. Under this part of the deal, Novell agreed to pay Microsoft $40 million in exchange for the latter company's pledge not to sue Suse Linux users over possible patent violations. Also "protected" are individuals and non-commercial open-source developers who create code and contribute to the SuSE Linux distribution, as well as developers who are paid to create code that goes into the distribution.

In mid-November, shortly after the pact was announced, Microsoft chief Steve Ballmer said companies that sell or run Linux, but aren't covered under the Novell deal, are illegally using Microsoft's IP. "We believe every Linux customer basically has an undisclosed balance-sheet liability," he said.

He said in a later meeting: "I do think it clearly establishes that open source is not free."

Novell disagreed, with chief executive Ron Hovsepian saying in an open letter: "Novell did not agree or admit that Linux or any other Novell offering violates Microsoft patents."

In announcing its deal, Dell said it sees the patent-protection side of the agreement merely as a kind of insurance policy adding an extra layer of comfort for Dell customers.

Linux users made their annoyance clear on Dell's IdeaStorm suggestion-box website, which lay behind the initial decision to pre-install Linux on desktops.

One suggestion urged Dell to "End the Novell/Microsoft Deal". Another suggested: "Don't cooperate with Microsoft for Linux".

A third argued Dell should clarify the situation by making "an official statement that they do not believe there is any Microsoft intellectual property in any of the distributions of Linux they offer". This suggestion received several hundred votes, but was also heavily demoted by argumentative Microsoft fans.

"By doing this, Dell has lost the support of all the Linux people - basically the people who were about to go and buy Dell/Ubuntu laptops," said one IdeaStorm user in a comment on the site.

In the meantime, Novell has lost another star Linux developer, with Robert Love, who had been in charge of Novell's desktop Linux efforts, announcing his resignation on Friday.

Previous open source departures include Suse founder Hubert Mandel, Samba founder Jeremy Allison, Linux advocate Ted Haeger, Linux impact team head Walter Knapp, Samba team member Guenther Descher and others.