Adobe Systems, Inc. is expected to file an antitrust lawsuit against Microsoft due to a dispute over Microsoft's use of Adobe's PDF (Portable Document Format) software.

Microsoft's Office suite currently includes PDF support, but Adobe wants its software to be removed and offered for a fee. The widely used PDF software allows users to create electronic documents and books.

Microsoft previously included PDF support in test versions of Office 2007, but has opted to remove PDF from the suite entirely. (Source: macworld.com)

Instead, Microsoft is integrating its own PDF/Postscript competitor, known as the XML Paper Specification ("XPS") into Windows Vista. (Source: zdnet.com)

An XPS document is a "paginated representation of electronic paper described in an XML-based format. The XPS Document format is an open, cross-platform document format that allows customers to effortlessly create, share, print, and archive paginated documents." (Source: microsoft.com)