In Visual Studio, add the XML file to a project. Open the XML file. When the file is open and its window is active, you should see, in the Properties window, that you can specify an output filename and a stylesheet. Also, you should see that the menu bar now contains an "XML" item.
If you pick "Start XSLT Debugging" or "Start XSLT Without Debugging from the "XML" menu, VS will apply the specified transform to the XML file, write its output to the file you specified, and then open that file. If the file has an .xml extension, it'll open it in a text editor window; if it has an .htm extension, it'll open it in a browser window.