Hi Markus--
You should also consider default ***services (reached by typing services.msc
in your run box) that you might not need. Jupiter Jones' reference is a
good one for processes. Here are some links for service guides.
If you don't have hardware or software that is connected to some of the
default services in Vista, then they don't need to be automatic and started.
For example, if you're not using mobile devices in conjunction with your PC,
you don't need services for them always started and automatic. You can turn
them off and if the need arises, turn them back on.
Vista Services Guide Part 1
http://www.tweakvista.com/article38662.aspx
Vista Services Guide Part 2
http://www.tweakvista.com/article38664.aspx
Good luck,
CH