Guys, it seems to me that a healthy respect for the dangers of spy-ware, ad-ware, other mal-ware, and hackers is not paranoia--the bad guys, like it or not, are out there.
I have a firewall built into my router, and I use (in alpha order) Ad-Aware, Norton Antivirus, PCPitstop Optimize, Registry Mechanic, and SpyBot Search and Destroy. Many run weekly via Task Scheduler; I run the others weekly, more often if it seems appropriate. They all catch something the others have missed, no matter what order I run them in. That's because they all have different algorithms and look for slightly different things.
No, not all cookies are bad. They're very convenient for things like identifying you to web sites so you don't need to log in every time. The programs I use leave those cookies alone. Some cookies, however, keep track of what sites you go to--and report the information to people who generate ads. My programs identify those cookies and delete them. PC Pitstop Optimize also gets rid of unneeded stuff like temporary files, and thereby helps performance.
I'm not recommending these specific programs: choose what you will. In fact I may be changing my choices as subscriptions come up for renewal. But protect yourself, guys. It's not paranoia, it's just smart.
Barnacle