http://www.guavi.com/vpncheck_pro_computer_id.html Is this true? What is computer name or hostname? The name you give your PC? How would that be used to track someone on the internet Even if some one has a simple algorithm to track your Computer ID patterns how would they track it to an individual?
There are many ways to trace a computer, a lot of fingerprints that can be analyzed. A VPN is a good thing but it won't do much good if you've left you're real identity in some file that a javascript routine could access. Looking at the source of this and that they are trying to sell a product through paranoia, I wouldn't take it too seriously. An article that can actually list privacy vulnerabilities that can slip though a VPN would be better.
Javascript could be used to access information stored locally on a computer and your browser settings. If you had something like a plain text file with information about yourself, it could be vulnerable. The VPN just encrypts what is passed though its tunnel and hides your real IP. I wouldn't worry worry about torrents. It is your browser that is a weak point. You should read some of the threads in the Privacy Technology section here. They cover a lot of this.
I'm assuming that you mean in Windows. On Windows 7, go to Start, right click on "Computer", and hit "Properties". Then click on "Change settings", which opens "System Properties". Then click the "Change" button, edit the computer name, and hit "OK". In Linux, open a terminal. Run "sudo hostname foo" to rename the computer "foo". I'm sure that there's a command line way in Windows.
