I like the speed and compatibility of IE, but I like the tabbed interface of more modern browsers, so I use AvantBrowser now. It uses the IE engine for compatibility, but has the tabbed interface and customizability of the modern browsers. Just my two-cents.
http://www.avantbrowser.com
But wouldn't a "skinned" version of IE still have all of the security problems of the original? With Firefox, you get the functionality as well as reliable security.