NewSID

From Microsoft: Many organizations use disk image cloning to perform mass rollouts of Windows. This technique involves copying the disks of a fully installed and configured Windows computer onto the disk drives of other computers. These other computers effectively appear to have been through the same install process, and are immediately available for use.
While this method saves hours of work and hassle over other rollout approaches, it has the major problem that every cloned system has an identical Computer Security Identifier (SID). This fact compromises security in Workgroup environments, and removable media security can also be compromised in networks with multiple identical computer SIDs.
Demand from the Windows community has lead Symantec and Altiris to develop programs that can change a computer's SID after a system has been cloned. However, Symantec's SID Changer andSymantec's Ghost Walker are only sold as part of each company's high-end product. Further, they both run from a DOS command prompt (Altiris' changer is similar to NewSID).
NewSID is a program we developed that changes a computer's SID. It is free, comes with full source, and is a Win32 program, meaning that it can easily be run on systems that have been previously cloned. NewSID works on Windows NT 4, Windows 2000, Windows XP and Windows .NET Server.