This is a pretty vital discussion, and one I rub up against every day. The answer has to be something that can be easily understood by everybody involved: clients, account managers, back-end people. Just today a colleague was confronted by the requirement to sort out a strange peekaboo background image error in IE6. It seemed pointless to be spending effort “fixing” such a thing – the only real fix would have been to remove the background image altogether. The point is: this lack of a common understanding is a waste of everyone’s time. We all should “support” IE6 – our clients’ sites should be usable, and should take money, on that browser. But we should also promote maxims that blow apart commonly held misconceptions. Most people don’t hold it as a truism that web pages don’t have to look the same in every browser – to many people this is, by default, what “support” means. So step one should be scoring this on the minds of all around us:

Web Pages Do Not Have To Look The Same In Every Browser.

…then we can go from there.