how to detect if browser supports xhtml

[kyoshu]

to detect if browser supports xhtml i use:

#!/usr/bin/perl -wT
use strict;
use CGI;
my $q = new CGI;
if ( grep { /application\/xhtml\+xml/ } $q->Accept ) { print "Content-
+type: application/xhtml+xml\n\n"; }
else { print "Content-type: text/html;Charset=utf-8\n\n"; }
print 'some xhtml';
...

is there any more advanced way? module, or how you do it?

20050602 Edit by ysth: remove pre tags, add code tags