If you haven't had a chance to check out IE 8 beta or RC, then you're doing yourself a disservice. This is the most secure IE yet. Not only is it more secure than any other IE, but it's also the most stable. If you're been suffering the slings and arrows of IE 7 and browser crashes, you'll be pleasantly surprised by the shiny and new IE 8.
From a security point of view, one of the areas that you'll be most impressed with is the cross site scripting filter improvements in IE 8. Check out the details of these improvements at:
Thomas W Shinder, M.D., MCSE
Sr. Consultant / Technical Writer