Although Microsoft didn't announce general hardware requirements for Longhorn as expected at the Windows Hardware Engineering Conference (WinHEC) 2004 trade show this week, company representatives did reveal that the graphics-card requirements for the upcoming system have changed since Microsoft first revealed them at WinHEC 2003. Microsoft also presented details about Longhorn's so-called tiered user experience, which the company calls Aero.
  
"The Aero user experience is a generational leap over what's available today in Windows XP," Kerry Hammil, a program manager on the Avalon team, said during a graphics session at the show Monday afternoon. "There will be two discrete levels of user experience in Longhorn. As graphics hardware becomes more powerful, the user experience becomes richer in discrete steps."
  
These levels, or tiers, are currently called Aero and Aero Glass; last year, Microsoft simply referred to them as the Tier 1 and Tier 2 user experiences. The default Aero user experience is built on the low-level Longhorn graphics API called Avalon and will require a DirectX 9-compliant 3-D graphics processor with at least 32MB of RAM and an Intel AGP 4x bus. Aero will require a minimum resolution of 1024 x 768 (XGA), compared with 640 x 480 (VGA) for today's Windows versions. Last year, Microsoft announced DirectX 7 compliance as a baseline for Longhorn, but Hammil defended the change. "By 2006, DirectX 9 will be baseline functionality," she noted, adding that finding DirectX 7 cards in 2 years will be impossible, anyway. "Machines with graphics hardware that doesn't meet this Aero bar won't qualify for the \[Designed for\] Longhorn logo."
  
Aero Glass, the higher-end user experience, will be a true superset of Aero and will come with higher hardware requirements. "Aero Glass will provide a beautiful \[UI\] experience with transition animations. Window frames will be a bit blurry and translucent, making text easier to read. Transparencies and animations will be hallmarks of the Aero Glass user experience, with more modern, high-quality visualizations than with \[standard\] Aero." Aero Glass will require a DirectX 9-compliant 3-D graphics processor with at least 64MB of RAM, although Microsoft will recommend 128MB to 256MB of RAM.
  
In addition to the two tiered Avalon-based user experiences, Longhorn will also support a legacy Classic display mode that will resemble the Windows 2000 UI. This mode will support all the non-UI-related Longhorn technologies, enabling Longhorn applications to run in Classic mode. Microsoft is providing this mode for upgrades that don't meet the minimum requirements for Aero and for corporations that would prefer not to retrain users as they migrate to Longhorn.
  
I'll provide more details about the Longhorn display architecture soon on the SuperSite for Windows . Also stay tuned to the SuperSite this week for more WinHEC 2004 coverage.