I installed the IE 8 beta in my Windows XP virtual machine today and now have an environment for testing IE 8, IE 7, IE 6 and IE 5.5. If you want to download the beta, here are some things to keep in mind…

• The IE 8 install overwrites IE 7.
• IE 8 has an Emulate IE 7 button in the toolbar.
• Switching between IE 7 and IE 8 rendering modes requires a browser quit and relaunch.
• If you use Multiple IE to run multiple stand-alone versions of IE, installing the beta may cause your stand-alone versions to ignore IE conditional comments.
• Uninstalling and reinstalling Multiple IE fixes the above issue.
• If you use the full Monte <!--[if IE]> conditional comment, IE 8 will see it and render whatever is in there.
• I haven’t notice a real difference between IE 7 and IE 8 rendering yet. I have lots of trouble getting past the hideous anti-aliasing, though.

I think I’m fully up and running with a reasonable means to test in all versions of IE. Remember, conditional comments for your various style sheets should be linked thusly (assuming you target IE 6 and 7 together in one sheet and then IE 6 by itself in another one like I do):

<!--[if lte IE 7]><link rel="stylesheet" href="/css/ie.css" type="text/css" media="all" charset="utf-8" /><![endif]-->
<!--[if IE 6]><link rel="stylesheet" href="/css/ie6.css" type="text/css" media="all" charset="utf-8" /><![endif]-->

Remember to use the lte (less than or equal to) operator when targeting multiple versions of IE that are less than or equal to a certain version number. IE 8 passes Acid 2, so you shouldn’t need to serve it any special CSS.