You might want to take a look at IE7.js.
IE7.js is a JavaScript library to make Microsoft Internet Explorer behave like a standards-compliant browser. It fixes many HTML and CSS issues and makes transparent PNG work correctly under IE5 and IE6.
Their IE9.js claims to:
Upgrade MSIE5.5-8 to be compatible with modern browsers.
I have not tested this myself with Acid or other standards tests, but this might be promising.
