Final answer:
To disable programs from automatically starting up on Windows boot, the best tool is MSCONFIG, which provides a way to enable or disable startup programs.
Step-by-step explanation:
To manage the programs that automatically start when Windows boots, the tool to use is MSCONFIG, otherwise known as System Configuration. This utility includes a Startup tab which lists all the programs set to start at boot. From here, you can enable or disable startup programs as necessary. Note that in the latest versions of Windows, this functionality has been moved to the Task Manager, under the Startup tab.
Other options listed, like Performance Monitor, Fixboot, and FIXMBR, serve different purposes. Performance Monitor is a tool to analyze system performance, Fixboot writes a new boot sector onto the system partition, and FIXMBR is used to repair the master boot record of the partition's boot sector. They are not related to managing startup programs.