For my sister her website (www.m-am.nl) I had issues with IE8 
Some rendering was not done properly, but it worked fine on IE7...
After some searching, I found the fix. Put the next line direct after <head>:
<meta http-equiv="X-UA-Compatible" content="IE=7" /> <!-- for IE8 Compatibility -->
And IE8 will be forced to become compatible with IE7.
So you have something like this:
<html>
<head>
<meta http-equiv="X-UA-Compatible" content="IE=7" /> <!-- for IE8 Compatibility -->
<title>Foo Bar</title>
</head>
<body>
<!-- website content --/>
</body>
</html>