You log in and your profile roams with you. It's called "roaming profiles". Today folk are playing cloud computing. I'm agree that's nice but have worries. More at link.
A while ago I came across some utility that mirrors your computers i.e. if you are working on one computer, more specifically browsing and later on want to continue that work on another computer, using this utility you can do that.
I am not too sure if this is a program or some browser extension. Does this ring bell?
Thanks in advance.