BossWebmaster, valid code on it's own doesn't have
SEO benefit, however invalid code can and often does hurt the ability of a search spider from reading the site thus the benefit of valid code. If an engine can't spider the site because of bad coding (or part of) then it wont' rank as well.
It's like tabless design doesn't give
SEO benefit by itself but what it does do is it allows you to place the elements in an order on the page (text view..like a spider would read it) that has very powerful
SEO benefits, and the CSS then can move those sections around and lay them out into an appealing design for the site visitor.