I'm not so sure about Vista/Win7 but Windows XP's tweakui allows a primitive form of "focus follows mouse." It doesn't work exactly like I'm used to with other

I'm not so sure about Vista/Win7 but Windows XP's tweakui allows a primitive form of "focus follows mouse." It doesn't work exactly like I'm used to with other managers, but it also doesn't require loading additional software (well, beyond going to MS' site and downloading tweakui).