I dont want to sound like I'm being unsensitive here, but why go throught all the trouble? do a search fro *.jpg, *.jpeg, *.gif and delete all of the entries that you find that exist in temp folders. Follow that link to the fuck ms page, and delete those history files as well.
Bottom line is that even if this guy was surfing kiddie porn for a few days the authorities are not likely to come looking for you. Now lets hypotheticly say they were going to bust a site that he looked at, your IP address will be logged on their web server, and they can supeona your ISP to verify your MAC address. So even if you dont have any evidence on your machine of the porn, they still know that at one point you viewed it form that machine.
BUT- with everything going on in the world right now, do you really think they would waste all that time, money, and effort to come and make one arrest? They most likely would just shut the site down, seise their computer gear, and sell it at auction...and everyone goes home happy.
I wouldnt be sweating this one out if I were you...
bern