Pc Running slow, CPU utilization High!

[amberonline24]

My cpu generally runs with high utilization, but after some time it goes on 80-100% utilization which slows down my computer drastically.It does not hangs but starts responding slow.Average temp. of CPU is always between 60-70 deg. Celsius ; and fan runs between 2300-2700 rpm.could any one suggest me whats wrong with my CPU. Any help is appreciated.
My PC confg. is:
Jetway G41 Chipset motherboard,
Pentium D 2.8 GHz(smithfield),
Seagate 80 GB 7200 rpm,
Kingston 2GB DDR2 800MHz,
200W PSU,
Sony DVD writer,17"CRT,
windows 7 Ultimate.

[JJ 3000]

Are you seeing the 80-100% in task manager?
Do you have a lot of processes and or services running?

[Allan]

What process is eating the cycles?

[amberonline24]

What process is eating the cycles?

The software which is running,eg.internet explorer,download manager.
and if i close all windows then windows explorer is eating the cycles.

[amberonline24]

Are you seeing the 80-100% in task manager?
Do you have a lot of processes and or services running?

Yes.In the task manager and in CPU meter gadget.No,i don't havemany processes running.

[Allan]

Please follow the instructions in the following link and post your logs in the thread you create (NOT in this thread):
http://www.computerhope.com/forum/index.php/topic,46313.0.html