Such as this one: http://www.webstandards.org/upgrade except it's just awful and is way out of date (use Netscape 7? really?)
I am going to require IE9+ and the latest versions of the rest of the browsers.
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I don't think you should require IE9+ and the latest version of all other browsers. You're going to be rejecting an awful lot of potential visitors. Can your website really not handle IE8, or Firefox 15? What you really want to do is redirect visitors with ancient browsers which isn't too many IE6 maybe IE7 right?
So your best bet is to have a FAQ or support site. Desk.com offers 1 free seat it's a great web app which you can setup a cname to such as http://support.yourdomain.com then have a FAQ similar to the one on the website you posted about upgrading your browser and how your site doesn't support old browsers. This way the visitor never leaves your domain and you can at least keep engaging them with your content as long as possible. It's easy enough to link to the latest browser download pages. Why not do it from your own domain?