There are indeed many approaches to producing multi-column flexible layouts that do not require horizontal scrolling in order to display all content. Here is a depiction that uses floated left columns (boxes) -- Here a real life three column application
Web Developer Tool Kit - for creating Standards compliant and Interoperable web pages
W3C Markup Validation Service - validate HTML code for reliable rendering in all Browsers
WAVE accessibility evaluation tool - check page structure, image alt text, form labels, etc.