For my part I wanted to use rounded borders using css. IE8 on Vista does not support such. And since the graphics were so that the rounded borders would show a nice rounded shadow as well, the page looked terrible in IE8.
I tried using conditional comments, but to no avail, IE8 would not evaluate the if IE expression and thus would not include the external stylesheet.
Then I had a look at putting it into quirks / compatiblity mode, however, this still did not work as the CSS hacks I had used did no longer work for the IE8.
Last but least I found a working CSS hack that will render the page correctly when in compatibility mode.
* + html #test[id] { color:lime }
Now, I do not know if this works for IE7 or below, so you would have at least three
different hacks for each IE release you want to support, e.e.
* + html #test,
html+body #test,
* html body #test
{ color:lime }
I wonder what the next regression of the Internet Exploiter will behold for us.