WordPress and Valid HTML

Does anyone else have issues of valid HTML with WordPress? I am having real difficulty in finding a theme that maintains valid code, especially after the implementation of widgets. As I am not a web developer (and I really have no interest in becoming one!), I like the functionality and control that WordPress gives. However, as I am also a convert to web standards, valid HTML and all that comes with those, I am frustrated that I am can’t manage to keep my WordPress generated blog on the straight and narrow.

Do you have any ideas? Any leads?