Remove the spots, by cleaning your glasses, now lets speed up your system.
#1 clean out All system caches, including browsers, java, adobe etc.
#2 goto controlpanel, administrative tools, services, disable all the services you don't need.
#3 do a control-alt-delete then taskmanager. Look at all the processes you have runnning you don't need, you might have to go back to services to end them, you might have to uninstall programs etc.
#4 clean out registry, fixes lots of trash interference in computing, and defragging makes the HHD respond faster.
#5 Open up your brower, check your homepage has not been hijacked, and go in and disable add-ons you don't need.
#6 Hijackthis is a small program if your tech smart, to be able to remove runstatements, and get rid of bugs like run once statements that become redundant, and a few other issues. Use under tech guideance.
#7 factory REset your router. Go into the router webpage, flush, reset, and completely on your system delete and setup new control points.
#8 remove any toolbars, and other unexplainable programs you have in ADD n Remove programs.