You can check out Sitehound over at
Firetrust. It has a fully functional 30-day trial option you can download and try out. Unlike some other trial packages - most notably the new ZoneAlarm 7 Free - Sitehound completely uninstalls if you elect to not keep it. If you want a program where you can be actively involved in helping fight the bad guys, and at the same time, learn about how it is done, Sitehound is a good option. It provides lots of information.
If you currently use IE7, then check out the Phishing Filter as it does much of the same thing, but is less intrusive on your desktop and may be better for those that do not want to be that much involved. It is important to note that neither program will allow you surf the net haphazardly - you still have to buckle-up and keep your hands on the wheel!
I use AVG Pro for my AV scanner. The free version is just as effective as a scanner, but the Pro gives you much better scheduling options, and more information about suspicious activity.
I leave my systems on 24/7/365 so every night, AVG checks for updates, then scans. Same with my anti-spyware scanner. In this way, when I get up in the morning, I get my scan reports and my systems are ready for a day's work.
Note that most experts would say it is better to allow your systems to scan when the computers are not in use. This ensure the fewest number of programs are running, and the fewest number of open files. If you are using your computer while scanning, the scanners will skip many files, and have to compete for resources.
Note too that every scanner will have an adverse affect while scanning. That should be expected as there is intense hard drive activity. But certainly Norton has been known to affect performance more than others, but at all times, not just during scanning. To be fair, I hear the latest version is better.