There is a free program that you can run to help you determine the programs that you can stop from running. It is called Process Explorer.
"The Process Explorer display consists of two sub-windows. The top window always shows a list of the currently active processes, including the names of their owning accounts, whereas the information displayed in the bottom window depends on the mode that Process Explorer is in: if it is in handle mode you'll see the handles that the process selected in the top window has opened; if Process Explorer is in DLL mode you'll see the DLLs and memory-mapped files that the process has loaded. Process Explorer also has a powerful search capability that will quickly show you which processes have particular handles opened or DLLs loaded." [More]
Once you have Process Explorer installed and running:
1. Click on the CPU column to sort processes by percentage of CPU usage.
2. Select the process that's using most or all of the CPU percentage.
3. Right click the selected item and from the options listed, select 'Google'.
This will invoke a Google search on this process which will give you enough information to make an informed decision whether or not to stop this process.