Ok, so I uninstalled Spybot but I still have some programs eating up some of my resources. Do you know either of them and if I need them running or not?

dwm.exe - eating up about 15K in resources (described as desktop windows manager)
explorer.exe - eating up about 18K in resources (described as Windows Explorer)

Also, why is my CPU usage so high (usually over 40%) but when I open the Windows Task Manager - just opening it, not turning anything off, it immediately drops back down below 20%?