To elaborate... In order to have Single Sign On, where all user information is stored on one computer and users log in to the domain, not the individual workstation, you are going to need what's called a Domain Controller. A domain controller provides authentication for the domain - all user accounts, their passwords, etc. are stored on the server, thus people can log on to any computer on the domain with the same username and password. Doing this will require you to have an operating system capable of being a domain controller. Generally speaking, this means you'll have to buy a copy of Windows Server 2003, any version except for web edition. When you get the server up and running, let us know and we can get you started on creating a domain. If you don't have too many computers/people and if you don't have too much money (Windows server costs several hundred to thousands of dollars when you factor in the license cost and the cost for CALs for each user or computer), then you might want to look in to a free alternative. Getting a linux server up and running with Samba can emulate a Windows NT 4 style domain. It's not as good as active directory, which you get with windows server 2003, but it's way cheaper. If you've only got a few computers, this might be the way to go. Alternatively, if you don't feel comfortable setting up a linux server, you could look into SME Server. It's pretty much id***-proof. It has a wizard-like setup interface, and all configuration after you get it up and running is done through a web interface that is accessed by a regular internet browser across the LAN. I've tried it before; it's pretty good for a small setup. So, let us know about how many users/computers we're dealing with, and what your budget is and we can give you more help. By the way welcome to MSFN. P.S. Is there a mod out there who can move this to the NT forum, since this is more of an NT issue than an XP one? Thanks.