I think most of the posts have it bass-ackwards. The people who make the sites have to support their users. Making them upgrade arbitrarily is stupid. It just makes you look like your sites is broken or has requirements that others do not. Ideally, sites should go ahead and make their sites work on most browsers that their users visit them with, and if the older ones, just work, but have some legacy issues that only affect "clean lines", I think that's fine. (Example, lack of alpha blended transparent png). Considering the complexity of making a standards browser that is competitive, free, fast, able to render broken pages without crashing, and is also professional looking is an incredible challenge. To be honest, I'm surprised the web still works considering all the mitigating factors.