With more and more people embracing the mozilla firefox browser everyday, looks like its time for web developers who wrote IE specific pages to take a second look at their pages.IBM developer works recently published this article titled "Migrate apps from Internet Explorer to Mozilla" which discusses this very activity. Personally, i believe it would be a better idea to make these web pages W3C compliant so that tommorow should we have an even better version of a browser (swoon!) the migration shouldnt be required (of course, a *better* browser would be W3C compliant right?). To check whether your web page(s) are W3C compliant (which in simple terms means it sticks to the norm rather than using g browser specific HTML tags), run them through W3C Validator. There's one for your stylesheets as well.
For those who are still going to stay with IE, think of this, your web pages are not going to render correctly for IE7 either. As Molly says "Thats Why its called Beta" - To begin with, there’s the not-so-small fact that in a standards compliant environment, browser sniffing of this nature shouldn’t even be necessary.