Alright you can do the VPN thing with the internet connection wizard in XP, you can accept incoming connections and make a remote connection! pretty easy, however I'm not a big fan of Microsoft stuff, so If you are looking for an outside solution for the VPN part check out the below link..
http://www.freedownloadscenter.com/N...PN_Server.html
now as far as reporting ppl that login to the computer. You would want a program like BlackICE, as I'm also not a fan of that, just use zonealarm its free, and you can always do a manual whois lookup on the IP addy and report them to the abuse address at there ISP that way. And you can always report them to a state or federal agency address.
I'm really tired, so everything I wrote may be totally off subject and if it is please let me know, I'm going to bed now!
Later,
~PCTech