|After running Malwarebytes, update your antivirus program and run that also, Safe mode is best if you suspect a problem.|
UNinstall programs you never use, especially those that were included with the computer that you have no use for.
Run msconfig and go to the Start Tab, Uncheck all except Microsoft and your antivirus program, Apply and Restart the machine.
Run Disk Clean Up - repeat monthly.
Clean out your browser's History, Cookies, Temp Internet Files, Etc. - repeat weekly.
Disable or delete browser add ons you really do not need.
Install Process Explorer (from Microsoft) to better monitor your running processes.
If all else fails, back up and do a factory restore and updates again.
Better yet, reinstall from a new Retail version of Windows 7 and only install drivers from Gateway's site. Most factory installs, you would be doing good if your idle reaches over 85% but with good maintenance a clean install should be capable of idle processes of over 98%. If there are not any updates waiting in the background, my system typically will sit between 98% and 100% idle until I launch something.
You have to be a little bit crazy to keep you from going insane.