Is there a html conditional statement for everything not Outlook?

Try this:

<!--[if !mso]>-->
  content targeted at non-outlook users goes here...
<!--<![endif]-->

To prevent statements being stripped in outlook.com, change <!--> to <!-- --> -

<!--[if !mso]><!-- -->
    All Except MSO 07-13
<!--<![endif]-->

Super late response, but hopefully this will help someone. This worked for me:

<!--[if !gte mso 9]><!---->
<p>I'm not Outlook 2007/2010.</p>
<!--<![endif]-->

Edit: Answered above, but extra tags on the IF statement are to hide the tags from being revealed in IE7/8.