How to use HTML5 in IE 7?

Question

I was wondering whether there is a way to make html5 code visible in Internet Explorer 7 or less.

For example

Answer 1

I check whether or not the requesting client supports the application/xhtml+xml mime type (it is part of the accepts header sent the request).

If it does not, then I send the client a version of the page using div nodes in place of most html5 semantic nodes.