Where is the evidence to suggest that visiting http://validator.w3.org and having a compliant site is in any way going to help your organic search rankings? Every site that is kicking my butt out there not only fails validation but with 100's of errors. Where is the evidence that customer's care? One of my competitors is closing in on 43 million dollars this year - somehow I don't think he cares if his site looks the same on all browsers. In fact there is some evidence to suggest that sites that pass validation don't perform as well on Google but do better on MSN. And I don't think customer's care if your borders on IE are blue but on Mozilla are grey. As long as they don't have to scroll too much and as long as the page loads reasonably fast - customers could care less about valid HTML.

I have a site that doesn't validate and I have over 450 pages. I am not too unhappy with how my site appears across different browsers and so before I spend 100's of hours in an area that in the end may have little impact - I was wondering if you could point me to specific case studies where valid html was worth the effort and led to a higher ranking and an increase in the conversion from visitor to sale.

Thanks