|You could just ask him to stop deleting the history. He could go into InPrivate Browsing, which will delete his browser session and should keep all non-InPrivate Browsing information.|
You can also disable InPrivate Browsing and ability to delete browser history via the Group Policy editor. Go to Start > Search bar > type: gpedit.msc
Direct yourself to Computer config > Admin templates > Windows compoments > Internet Explorer
> InPrivate > Turn off InPrivate Browsing > set to Enabled
> Delete browsing history > Turn off "Delete browsing history" function > set to Enabled
Those were the steps for Windows 7, and I'd assume Vista would be very similar.
Apologies if I don't respond to your reply immediately. I don't check this site daily.