As says forthehandyman, HFS does not add anything to the registry, except if you want to save to registry. That's why you can have hfs with his filesystem on an external drive and  conect it to every PC without instalation (you have only to care for open port and firewall). I had also running different versions for internet and lan at the same time.
It's worth to mention that HFS is what I call a clean program ! 
Saving every shit to registry is what slows down all window machines with use, and you have to use rcleaners and stuff like that.