Tracking a users actions

I have a user in my enterprise that has just been accused of a crime
against a child and I have been given the task of going through his
computer on a hunt to find if there is any “inappropriate” material on his
drive including Internet History. The files and such I can handle, but if
he’s cleared out his browsing history, is there any way to get that back?
What is the easiest way to go about checking his internet history? I’ve
never had to do this before and any help would be fantastic.
He is using IE7 on his computer, OS is WinXP Pro w/ SP2 working in a
Domain environment.

Thanks…