IE9 is the Current Most Secure Web Browser Against Socially Engineered Malware

IE9 is only available for Windows 7 (and Vista if you have to use that).  Don’t worry though XP users, IE8 is right behind at number 2 in the new malware study performed by NSS Labs.
NSS Labs Web Browser Group Test Socially-Engineered Malware 2011
IE9 also boasts some impressive browser speed improvements. With hardware accelerated video and graphics, IE9 is FAST.
See 9 reasons to get Internet Explorer and Download IE9
Also, make sure you read on how to use an add blocking add-on such as Simple-Adblock with Internet Explorer.  Now if only IE9 could sync bookmarks easily.