Working for a school these days, during our student office hours, we get a steady diet of infested Vista and W7 laptops. IE is an ever popular attack vector. And there are so many autoload points now that a quick manual cleanup is neigh-on impossible.

The Alureon/TDL rootkit has grown the capability to circumvent W7's signed driver mechanism so if you do get W7, expect your Google search links to go anywhere but the intended destination on of these days...