For scheduled reboots of Windows 2000/2003 systems, I was always using a version of SHUTDOWN.EXE (by Stephen L. Bryant from Microsoft) that did this job very well. However, I also tried using this one to do a scheduled shutdown, and that did not work well: Windows did shut down but the machine did not.
A colleague of mine found this one, which does this job quite well.
For those of you curious why anyone in his right mind would want to do a scheduled shutdown, here's the reason why: we are running VMware Workstation and one of the VMs is a Windows 2000 Server. We need to backup both the host server and the Windows 2000 Server VM, but we do not have enough licenses for the Windows Remote Agent of VERITAS BackupExec. So, the nicest option of course would have been to purchase another license of the Remote Agent, but instead we shutdown this machine just before the backup runs so that we can backup the VM as a regular file.