This does not work because of reasons already stated, but if the goal is to produce good code, and code that works in multiple environments, then it is a good idea to use a separate css file for specific browser overrides.
For IE - you also want to use the < ! -- if IE lte 6 -- > tag to specify if Internet Explorer Less than or Equal to version 6 so that you can target the right overrides for the right browser.
Why do you guys keep posting this garbage? Obviously you have not taken the time to research the future of IE. IE7 WILL recognize the important tag, therefore rendering this whole solution useless. If you want a temporary fix that won't screw up in the future you should be checking out the holly hack!
For IE - you also want to use the < ! -- if IE lte 6 -- > tag to specify if Internet Explorer Less than or Equal to version 6 so that you can target the right overrides for the right browser.
~Jeremy