How can I configure the local machine to perform a task at a set time?

A. Use the at command, e.g. for a job to run every weekday (like a backup)
C:\ at 20:00 /every:M,T,W,Th,F "<command string e.g. backup>"

For this to work the Schedule service must be running with can be started from the Services control panel applet or via the command line

C:\> net start schedule