The class action lawsuit against Microsoft's "Vista Capable" marketing campaign, which we first told you about in late February, got even more interesting late last week with the release of more emails between Microsoft and Intel and between HP and Microsoft.

According to a filing released Thursday (links to PDF file), the Vista Capable program originally included support for the Windows Driver Display Model (WDDM) as part of the requirement for support of core Windows features. Although OEMs such as Dell, Sony, and Fujitsu all asked for waivers from the WDDM requirement for various computer models that used Intel chipsets with integrated graphics that could not run WDDM drivers, Microsoft refused all three companies' request for waivers because of the improvements in stability and features resulting from WDDM drivers.

However, when Intel came calling on Microsoft , it was a different story. After a series of email exchanges between Intel and Microsoft, Microsoft dropped the WDDM driver requirement, enabling Intel and its OEM partners to market systems with Intel 915 integrated graphics as being "Vista Capable" - even though their integrated graphics would never support Aero Glass or be supported by a WDDM driver.

Although Sony was happy with the change, Dell was confused by the differences between Vista Capable and Vista logo PCs, and HP, which had switched to using ATI and nVIDIA-based integrated graphics that could run WDDM drivers, was furious with the change, as the change confused the differences between HP's WDDM-compatible products and other vendors' WDDM-incompatible products by labeling all of them as "Vista Capable."

Friday, more emails were released (links to PDF file), making it clear just how unhappy HP was with Microsoft's move. In one, HP's Richard Walker writes a scorching note to Microsoft's Keven Johnson and Jim Allchin:

I can't be more clear than to say you not only let us down by reneging on your commitment to stand behind the WDDM requirement, you have demonstrated a complete lack of commitment to HP as a strategic partner and cost us a lot of money in the process...I have engineers who've worked their tails off to qualify new platforms to support WDDM who are wondering why they put so much effort in when Microsoft changed the rules at the last minute and didn't even consult us before making the announcement.

As more information comes out about the "Vista Capable" fiasco, regardless of how the lawsuit is decided, one thing is clear, as I see it: a operating system logo program sticker is only as good as the requirements needed to achieve it. Here's hoping that Microsoft won't try a similar stunt with Windows 7.

On a personal note, I got lucky with my early 2006 HP notebook purchase; thanks to HP's switch to WDDM-compatible integrated graphics chipsets, I can run Windows Aero on my aging single-core laptop. However, most other laptops of similar vintage can't. What did you find out about the integrated graphics in your laptop or desktop when you tried Vista? Were you surprised to discover you couldn't run Aero? Hit Comment and tell us what happened.