As much as I would like to see Linux displace Windows in these kinds of environments, there really aren't any systems that give you the same kind of management functionality as Userlock, or even Active Directory and Group Policy. It's possible of course, but only if you have the time, skill, and manpower to rig something together yourself. I'm sure I'll get flamed for saying this, but the Linux desktop has a long way to go before it can even hope to be a viable alternative to Windows in the enterprise. Even then it will not be possible unless that particular segment unifies around a specific distro. Not saying I like it; just being realistic. It certainly doesn't stop me from going all Linux at home, but it makes it an unthinkable idea to try and sell to management. Hopefully this changes in the future, but it's a long way down the road.