It all depends on the kind of site you are building and the technologies involved. On some sites it may be ok to deliver a "less beautiful" web but with all the

It all depends on the kind of site you are building and the technologies involved. On some sites it may be ok to deliver a "less beautiful" web but with all the contents, in others it won't. Oftentimes nowadays you'll face a complete rewrite. In some recent projects I even worked hard to convince the client that it wasn't worth supporting IE8. It's not only that it loads faster with modern techniques (as CSS3 allows awesome effects that would need images/javascript with CSS2), but some functionality built around HTML5 would need a COMPLETE rewrite in Flash. Of course that means that if they insist on supporting older browsers not only that would mean a 30%-100% increase in price but new features the want afterwards will be more expensive as well (because you're supporting two different projects).