Ask HN: How do you handle unsupported browsers?

When developing our new website we made a decision not to support anything older than IE 8, and the newest versions of Chrome, Firefox, and Safari. The only issue we've found so far is that things don't always line up perfectly on IE 7, and we therefore would like to have a bar or alert (possibly similar to the message StackExchange shows for new users) alerting people that the site may not look perfect due to using an unsupported browser. What approach do you take/reccomend? Do you know of any sites that have it live so we can see it?

Thanks.