The safest way to stop these programs from running is to tell them not to run in the first place. If you look down by the time on your taskbar you will see a line of icons. Each of these icons indicates a program that is running. Hover the mouse over them to see what they are. Select one that you have decided is non-essential, for example, an icon for a media player update checker. Right-click on the icon to reveal a menu. From this menu select 'Options', 'Settings' or 'Preferences' (whichever appears). Look around these options and try to find one that says something along the lines of 'Run at start-up.' De-select this option and the next time you start Windows that icon should no longer appear.
You may find a few icons from applications that you installed and now never use. The best way to deal with these is to uninstall them. To do this go to 'Add/Remove Programs' in your Control Panel. (Comment to this article if you need help doing this. If there is enough interest I will write a beginners guide to removing applications).
Windows has a number of other ways to start programs: there is a Startup folder in the All Programs section of your Start Menu; there are settings in the mystical thing known as the Registry. To manage all these I use Mike Lin's excellent free Startup Control Panel. Follow the instructions on the Mike's website to install and run the program. A major advantage of Startup Control Panel is that you can remove the tick from the entries on the various tabs and see what the results are. If you then decide that you do need to run a program when Windows starts you can go back to Startup Control Panel and tick them again.
