There are a number of processes that can cause high % that are in fact normzal processes. eg if your disk has not been defragmented the saving nd loading of files willl using the normal process cause the processor count to go high.
There are also background normal processes that some manufacturers use to 'help' people use computers. these use norml processes but push the count up.
Have you slimmed down ALL the start up processes as some progs like Anti virus can push up the count although they should show in the task manager processes etc.
final thought ... have you cleaned out the fans particularly on the processor itself and also any cooling fins. if the processor heats up it has to work harder, the count goes up so does the fan rate and it may not be a process problem but rather an overheatng one!
M