Internet facing websites targeted for IE 7 may have problem in displaying pages correctly in IE 8. To fix the issue use the following fragement
<meta http-equiv="X-UA-Compatible" content="IE=EmulateIE7" /> to your master page
Refer the KB article from http://support.microsoft.com/default.aspx/kb/956197 and Randy Drisgill's Blog http://blog.drisgill.com/2009/03/problems-with-ie8-standards-mode.html
