Emails that show HP was enraged by Microsoft's decision to loosen the requirements for its 'Vista Capable' marketing campaign have been made public.

"I hope this incident isn't a foretaste of the relationship I will have with Microsoft going forward, but I can tell you that it's left a very bad taste with me and my team," Richard Walker, HP's senior vice president for its consumer PC unit, said in an email to senior Microsoft executives dated February 1, 2006.

One of those executives, Jim Allchin, who was in overall charge of Vista's development and delivery, was almost as outraged, and told his boss, CEO Steve Ballmer , that he was "beyond being upset" by the move. Ballmer denied being party to the decision.

The emails were unveiled by US District Court Judge Marsha Pechman in the class-action lawsuit that accuses Microsoft of deceiving customers in 2006 by certifying PCs as able to run Vista when it allegedly knew the machines were able only to handle the stripped-down Vista Basic, a version that lacked the new, heavily-promoted Aero interface, and other touted features. Vista was released early in 2007.

In early 2006, Microsoft relaxed the Vista Capable rules by allowing computers equipped with Intel's older 915 graphics chipset to qualify for the programme. Will Poole, then responsible for the client version of Windows, tossed out the requirement that a PC's graphics use the Windows Device Driver Model (WDDM), Vista's revamped driver architecture that debuted in Vista.

The decision pleased Intel, which had complained that it didn't have a sufficient supply of the more advanced graphics chipsets that would have met the original requirements. In fact, Intel's CEO Paul Otellini thanked Microsoft's Ballmer for the change.

HP, however, was anything but happy.

"The decision you have made has taken away an investment we made consciously for competitive advantage knowing that some players would choose not to make the same level of investment as we did in supporting your programme requirements," said Walker's email.

HP, unlike other computer makers preparing for Vista, had decided to ditch the low-end Intel 915 and 910 graphics chipsets to make sure that its low-priced PCs would be able to run Vista. In another email cited in the same group of messages, Walked said HP had designed and built two new motherboards for its upcoming Vista Capable lines. It was thought HP spent nearly $7m (£4.7m) on the technology to make its machines meet the original Vista Capable requirements.

NEXT PAGE: Ballmer denies involvement

Emails that show HP was enraged by Microsoft's decision to loosen the requirements for its ‘Vista Capable' marketing campaign, have been made public.

"Now we have a situation where PC manufacturers (and processor/chipset suppliers) can claim Vista Capable in a 'good' mode just because it will run," Walker continued.

"What kind of consumer assurance is that? Hardly one that puts any credence behind your desire to create the 'best possible customer experience for the Windows Vista Upgrade'."

Walker went on to tell Johnson and Allchin that Microsoft's credibility at his HP group had been "severely damaged" because Microsoft had "changed the rules at the last minute" without notifying HP.

Allchin fired off a blistering email to his boss, Steve Ballmer, within 10 minutes of Walker sending his message. "I am beyond being upset here. This was totally mismanaged by Intel and Microsoft. What a mess. Now we have an upset partner, Microsoft destroyed credibility, as well as my own credibility shot," he wrote to Ballmer.

"I was told this all started with a call between you and Paul [Otellini, the CEO of Intel]. I will have to get to the bottom of this and understand how we could be so insensitive to handling the situation."

Ballmer denied having any part in the decision to loosen the rules for Vista Capable by ditching the WDDM requirement, and instead put the responsibility on Poole's shoulders.

"I had nothing to do with this," Ballmer said in a reply to Allchin later in the day on Feb. 1, 2006. "Will [Poole] handled everything. I received a message that Paul was going to call. Will said he would handle it. Paul called. I had not even had a chance to report his issues when Will told me he had solved them. (it did not sound like he had) I am not even in the details of the issues," Ballmer said.