I was working on a site the other day and noticed something interesting. The tech support guy on the other end seems to have remotely logged into the computer I was working on, but without my noticing (or not very easily). I had my printers window open already but noticed that some of them were "auto-deleting" and renaming themselves. I know remote desktop (like VNC) can do this but at least it will show the other user what's happening. This one seems to be working in the background without any user knowledge. I would think that if I didn't have that printer folder open, they would have still done the same work, but this time without me noticing it right?

I searched this up a little and it seems to be VPN. From what I found, VPN is usually for file sharing only though. Will I be able to remotely access another computer without:

1. The user noticing it (no mouse movement seen or windows seen when I do things on my end).
2. Won't lock the user out when I'm remotely logged into their workstation (Windows XP kicks them back to the login screen)

I have searched more on this and XP has this feature built in, but just needs it to be enabled. There are some drawbacks as both sides (host and client machines) need to be configured for VPN access and it also looks like I need to forward the port (1723?) that it's using.

I found a program called Hamachi that can do this more easily but it seems to rely on their server. Is there a program out there that will work similarly but without a middleman? I want direct access so even if the server is down, it won't affect the connection.

Thanks.