How to create XPS files
Microsoft Office 2007 includes an add-in that automatically creates XPS files from office documents (Word, Excel, PowerPoint, ...). This xps add-in can be downloaded from the microsoft.com website.
How to edit XPS files
If you would like to edit XPS files, additional programs are needed, such as NiXPS Editor. NiXPS Editor is available on Mac and PC, and it lets you view XPS files, merge XPS documents or extract pages from them, edit/search and replace text in the XPS files, move or delete objects in an XPS file, change the color for various objects in the XPS document, export the XPS as a PDF, browse its file structure and extract elements, and nevertheless print the XPS files. You can download it here: NiXPS Edit
How to view and print XPS files
You can view and print XPS files using NiXPS View. NiXPS View is available on Mac and PC, and it lets you view XPS files, find a keyword within the XPS document, or print the content of the XPS document to your regular printer. You can download it here: NiXPS View
How to process XPS files in your application
If you are a developer and would like to include XPS files processing in your application, you need an additional program such as NiXPS SDK. NiXPS SDK has a C/C++ api's, but also a .NET api, and it offers you: fast native XPS processing, conversion to PDF, SVG and TIFF, cross platform freedom (works on Mac and PC), and much more. You can download it here: NiXPS SDK