Whoa, IE is displaying it as an xml file. Thanks, I'll look into that.
Seems to be a result of the usual MS-standard mis-behavior of ignoring MIME types. I got rid of the xml header and it seems to be fine now.
Imagine a pathologically idealistic, anti-religious, culturally-relativistic, iconoclastic, socially-irreverent, sociologically-progressive signature line here. Or don't.