rig getting laggy

[max power]

everyday tasks are starting to get laggy. opening a browser closing the browser, clicking a link ect. it takes the comp a few sec to perform an action.
checked for virusus and spyware. gigabyte k8nxp-sli venice 3200 @ 2.6
1gb corsair pro hitachi 250 X 2 raid 0 650w psu.

any idea's ?

 

[benjo]

Maybe a defrag is in order?

 

[Defcon5]

Id do a reinstall, suprising how much crap you accumulate