HTML to XHTML

[Lewis]

It has been some time since I last posted here.
Currently i'm considering moving from HTML 4.01 to XHTML since I think
it will make moving to HTML5 easier when that time comes.
No.

The thing is that I still need to support IE6.
So I wonder are the any problems with XHTML and IE6?

Yes. IE6 doesn't support XHTML, it simply treats it as HTML.

Are the in 2011 still reasons to stick with HTML 4.01 rather then XHTML?

XHTML should not be used. It is a dead-end.

I read in a book that rendering XHTML is faster, is that indeed so?

In theory, yes. In practice, not generally.