Click Tools, Interent Options, Delete Cookies, OK, Delete Files, check the box to delete offline content, OK, Delete History, Yes.
Then, open up the C: drive (Start, My Computer, C: drive), Documents and Settings, choose the User you are logged in as, Tools, Folder Options, View tab, under "Hidden files and folders" choose "Show hidden files and folders", Apply, OK, Local Settings, History, Edit, Select All, hit the 'Delete' key. Click Tools, Folder Options, View tab, check "Do not show hidden files and folders", Apply, OK. Be sure to empty the Recycle Bin.
You wouldn't believe how many guys at work I had to write this out for... Yeah, they were shopping for their wifes' birthday online... Uh-huh...
EDIT: Oh, and if she is running a firewall, be sure to "clean" it out as well.