The Expression suite is part of the Windows Presentation Foundation (WPF), a framework for creating user interfaces for desktop and Web applications running on the next-generation Windows Vista operating system. WPF is part of WinFX, an object-oriented, managed application programming interface for building Windows applications that can run on Vista.

Vista is due for release by the end of this year.

Scott Golightly, a consultant at Keane Inc., a Boston-based services firm, said that using Expression to easily import graphics and objects created by designers into XAML code will likely lead to improved user interfaces.

"If designers and developers both start using Expression and XAML, we might see a lot fewer applications that look like they were designed by developers," he said.

Microsoft will likely release a CTP version of Expression Web Designer during its professional Web developers conference in March, according to a source.