Does validating my sites code (with a tool such as the W3C validator) help my sites ranking in Google?
No, at least not directly. However, to the extent that cleaning up your HTML makes your site render better in a variety of browsers, more accessible to people with disabilities or folks accessing your pages on portable or other devices, and so on, it can improve the popularity of your site… increasing traffic, natural links to your site (which can help with your Google ranking), and so on.
