My CPU Usage has been relatively high, mid 80s-100% when I run more than one program. I usually run Skype as well as firefox, as I like to watch videos on blip.tv while talking to friends. I just bought this computer from a friend, it sat in a garage for at least 2 years, and I've already overclocked the CPU but it still has high CPU usage even when only one program is open.
Windows 7 Home Premium x64
Intel Core 2 Duo CPU E6750 @2.66Ghz
Asus P5E-VM HDMI mobo
6 gb Ram (2gb (2x1gb) Patriot DDR2-6400, 4gb (2x2gb) Ballistix DDR2-6400)
GeForce 9500 GT (1gb DDR2)
80gb Maxtor HDD (I just ordered a 1tb Seagate Constellation to replace this)
It seems whenever I have the video open, flash players CPU usage goes to at least 30. so the CPU usage whenever the video is visible is about over 60% that's without me running anything else that I want to run...
Have you tried Task Manager (CTRL + ALT + DELETE and choose start Task Manager) to see what processes are running and how much of the CPU is being used? You can disable services using MSCONFIG. You can "Google" the service name to be sure it is alright to disable it. I would also check Startup to see what is running.