|How are you trying to remove these things running in the background?|
There are two distinctive types of background items:
system files and installed applications (programs)both are controlled by certain services seen in control panel > admin tools > services
System files should be allowed as they are what makes your computer stable during operation.
The things you should be worrying about are start up applications that try to run in the background or at start-up...sending personal information back home and becoming resource hogs
Google for winpatrol a free and safe application that shuts down these applications but doesn't remove them or delete them.
As for a list of what is safe and not safe to disable (not remove)....visit blackviper or theeldergeek for a list of running services and the best way to shut down things.
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