Hello and welcome to the forums dbit.
As a rule of thumb, Windows 7 is built out of the box to be quite lean and mean without user intervention. This is in contrast to previous Windows editions where a fair amount of tweaking using 3rd party tools or the Registry is required to get the best out of Windows...
Services that you see running or doing things in the background often deactivate themselves when they have completed their upkeep, so they're not using unnecessary system resources if they don't have to.
May I direct you to this very useful tutorial that contains a compilation of common steps you can perform that will help you gain the best out of your Windows 7 system made by very own admin, Brink:- Optimize Windows 7
I think you'll gain quite a bit of insight there, and once again welcome and we hope you enjoy your stay here on sevenforums!