Give me a break. It is nothing to do with XPS, it is a file-extension/type problem.
Everyone better get ready to see XPS printers kick PostScript's butt in the mid to low end printer market. We just got a new network printer at work and they wanted $300 just for a downloadable PostScript engine for it. XPS will likely be a free update.
...and thank adobe for not letting MS include pdf creation.
Even though the PDF spec is now free to use, Adobe threatend to sue MS if they included it in Office 2007 or Vista.
Of course you can still download the Office piece.