Summarize:

This is in the lower left corner of the screen. You can also hit Win to perform this without the mouse. Checked indicates that the service is enabled, while unchecked indicates it is disabled. You can click Disable All to prevent all startup programs at once. This will save your changes and close the window. The deselected items will no longer launch on startup. You can also click Apply to save the changes without closing the window.
Click the Start button. Type "msconfig". Hit Enter. Click the Startup tab. Click the checkbox next program or service from the list. Click OK.