I suppose my main problem is that, by the time they reached XP, they should have realised how devious and inventive people are. I can forgive '95 and even '98 to a degree, after all, you can't expect a corporation of, say, 2000 programmers to outthink a quasi-community (which still sounds way too unified) of several hundreds times that number, but XP tries to be too helpful, and it was that 'helpfulness' that caused some of the larger security holes. XP wasn't what it could have been.
I suppose what needs to be done is for Windows to backpedal, and stop trying to be all singing/all dancing, and just to be a nice quiet operating system being inconspicious in the background, and not doing anything it's not being asked to do.