Computer hangs when asked to do anything.

My computer pauses doing anything and I mean anything, but it will perform the function asked in its own sweet time. I have all the latest windows updates and I ran a complete virus scan and used a program to updated my drivers.
Any & all help will be much appreciated.
TIA:D

Info on Computer

CPU Intel®Core™i7cpu 940@293Hz
Motherboard ASUS P6T Deluxe V2
Bus Type PCI Radeon HD 4822 Series
Bios American Megatrends Inc. Date 02/26/09
Memory 4096 MB
Video ATI Radeon HB 4800 Series (4890)
Speakers ASUS Xonor 1.3 Audio Device –Playback & Voice Playback
Sound Line in (ASUS Xonar HDAV 1.3 Audio Device
OS Windows Vista Ultimate (6.00.6002 Service Pack 2
64 bit (32 bit simulation mode)
IE Internet Explorer 8.0.6001 18813(Build 86001)
DVD/CD-Rom Drives Memorex 16X-DDL-IN SCSI Cdrom Device

can you open task amanger and monitor it see if anything is maxing out your cpu when you do anything?

monitor cpu usage under the processes tab