Though Windows XP has many advantages over previous Windows OS's, it doesn't block anyone from deleting internet history items - this capability lies in the browser you use. If you use Netscape, the history cannot be deleted - as far as I know at least! If you use Internet Explorer, all you have to do is open the history window (the icon that looks like a clock on the toolbar), right click on the site you wish to delete, then a menu comes up, one option is delete. Just click delete and it's gone. There are other options, like Properties, that you can see exactly what time the site was viewed and how many times it was accessed.
Just because an item is deleted from Internet Explorer's history, though, doesn't mean that it's gone forever. You can also check for cookies and in the temporary internet files folders. The easiest way to find these (the folders can be located different places on different computers, plus there can be multiple ones fo multiple user accounts) is to perform a search from the start menu. Make sure you click on Advanced Options in the search field and click to search in hidden folders Just search for "cookies", "temp" and/or "temporary internet files". This will give you little files that have been placed on your computer when a site is accessed.
I would like to recommend a peice of software called Activity Recorder. Just go to
www.download.com, then search for Activity Recorder. It's free unless you want to register it (I haven't found a need to). It records pretty much anything someone does on your computer and stores it in a little text file you can view later. If you decide to download this, let me know and I'll give you some tips, like how to put it into stealth mode so no one can tell it's running. It can be found, so either the person you're tracking should know about it or you can take your chances that they may find it.
Best of luck, hope this all helps. Let me know if you have any questions or if this all just was too long to make sense!
Have a great day!