Actually, there's one simple meta tag ("X-UA-Compatible") you can add to the head of your pages that will make IE8 use the IE7-compatible rendering engine:
You can also add the HTTP header to the response for these pages so you don't even have to touch the markup, just a configuration file on the Web server.
http://www.microsoft.com/windows/internet-explorer/readiness...
IE7 obviously isn't perfect (or even good), but it's also nowhere near as bad as IE6 in terms of supporting standards.