CPU usage very poor

It is normal for system idle to read around 99,as for the
system, it depends what you have running.Download a
spywear removal program and try that, also, go to start
run and type in msconfig and click on the startup
tab and see what you have running in the background, you
might want to uncheck some of those listed...Good luck.
-----Original Message-----
After a fresh reboot my comp runs at 0% CPU usage. After
I
run a program or two I notice a decrease in performance.
Games run slower...everything just gets slow. Even after
I
close all programs my CPU keeps running between 50-90%.
In
the Task Manager under Processes the two processes that
are using up the CPU are "system and system idle
process."
I've already deleted the bad Windows update everybody
keeps mentioning. I've also ran Disk Cleanup and Disk
Defrag. I've even went to Nortons website and did both
security check and check for viruses. Both came back
fine.
I'm at a loss. Please help!
.