XHTML and HTML are basically the same thing. You can just get away with being a little more sloppy with HTML than XHTML, but no one says you have to be sloppy. For example, XHTML insists that you close tags like </li>, which you can get away with not doing that in HTML. But I do it anyway, so there's no difference ... except that in XHTML you have some extra closing slashes that I find ugly, such as
<img scr="" alt="" <font color='"#FF0000"'>/</font>>.
The other problem with XHTML is that most Microsoft browsers don't actually support it (from IE8 and backwards). So you just have to serve it up as HTML anyway. There's a useful thread comparing them here:
Given that HTML5 is on the horizon, I consider XHTML to be a dead-end street (even though there's an acknowledgement of its rules in HTML5). Its usefulness was that it encouraged better coding practices—something that will be sorely needed with HTML5, which has gone back to allowing sloppy code.
Beaten to it.