Chrome browser w/ad block plus add-on + Panda Cloud AntiVirus (freeware) + Malwarebytes (freeware) = GOOD TO GO !!!
I would scan with Spybot first since it is pretty thorough. Then when it's clean uninstall it because it is a resource hog.
Look in task manager for anything that is taking up a lot of memory and or CPU when it is running slow. This may pinpoint the program that is slowing you down.
Sound money. Free market society. Personal Liberty. Ron Paul 2012