The most popular antivirus programs are targeted by virus makers. I mean they go out of their way to work around them and turn them off. I have removed viruses and spyware from "protected computers", including CA, Trend Micro, Norton and McAfee. I like VIPRE because I can install it on computers that refuse to install the other antiviruses, it doesn't slow your computer down and it's a good price at US$29.95 for 1 year. cheaper if you get 3 years.
Synchronise Automatically with your external hard drive. The cost of storage and external hard drives leaves no excuse not to backup your data regularly. I love handy backup for its ability to set and forget. It will backup, restore or synchronise at a scheduled time. It will email you each time your backup runs so you're aware if there is something wrong or at ease because of a successful completion.
Malwarebytes' Anti-Malware Malwarebytes' Anti-Malware is an anti-malware application that can thoroughly remove even the most advanced malware. It includes a number of features, including a built in protection monitor that blocks malicious processes before they even start. You can download it for free from their site http://www.malwarebytes.org/index.php
As you use your computer it collects all sorts of crap from the 'net. CCleaner is a freeware system optimization, privacy and cleaning tool. It removes unused files from your system - allowing Windows to run faster and freeing up valuable hard disk space. It also cleans traces of your online activities such as your Internet history. Additionally it contains a fully featured registry cleaner. But the best part is that it's fast (normally taking less than a second to run) and contains NO Spyware or Adware! :)