Great tool was released today by the XML Team (Webdata), from Microsoft.
Find it here: http://www.microsoft.com/downloads/details.aspx?FamilyID=72D6AA49-787D-4118-BA5F-4F30FE913628&displaylang=en
It's a .NET Framework 2.0 application which can be used as a simple raw XML editor. It's got XSL support, XML differentiation, XML Schema validation, entity name intellisense, and, as the name suggests, it's as simple as notepad.exe. Superb performance on large documents, too.
Great. Tune it up, change the icons and layout then ship it with Vista, I say.
I find it quite attractive, since nowadays I don't spend as much time looking at angle brackets anymore.