Useful DOS commands that I use infrequently and sometimes sit pondering what the correct executable name is:
msconfig - You can change ini files, what loads on your system (services and programs).
msinfo32 - Show details about your hardware and software.
regedit - GUI for modifying the Windows Registry settings.
ipconfig - Shows your TCP/IP address and associated information.
netstat - Displays network statistics and current TCP/IP settings. netstat -a to show all connections and listening ports