I know some purists insist that all websites should pass the W3C validation suite but I am more concerned about the big picture; making my website accessible to as many people as possible by not using non-text items (e.g. graphic buttons) for navigation, and using HTML constructs appropriately. A lot of the purists use tables for layout and then bitch about not passing the W3C validation - they worry about the letter of the law without understanding the spirit of it (W3C recommends against using tables for layout of anything but tabular data).