We should clean our PC’s inside out with anti bacterial detergent. It won’t be long or we see advertisements for that. I always get a bit iffy when I see commercials on TV for anti bacterial hand wash and detergent. Though these days we have an increased risk to get infected with serious diseases such as the swine fly, bird flu, SARS and what else the future has in store for us, the increased hygiene also seems to increase allergy cases and make bacteria resistant. , 
We could ask ourselves the same about our PC’s. I had the joy the other day to reinstall my iTunes. I downloaded the latest version and overwrote my previously downloaded installation file. Then I tried to install iTunes which did not work. After wasting some precious time researching, it turned out that the antivirus program was interfering. I have not wasted more time to find out whether it corrupted the installation file during the download or that it interfered with the installation process. Anyhow, the antivirus program did a bit too much and turning it off resulted in a successful download and installation.
Along the way I also found out that uninstalling iTunes does not remove everything. Not a big surprise because since the invention of software installation there have been problems with uninstalling software. Parts of iTunes remain installed and active (GEAR drivers for CD/DVD burning), parts of the files remained on disk and many registry entries stick around; all just there as contamination to your system. It all just slows your system down and makes your PC less healthy. These problems do not just occur with iTunes but with many software packages. In this case the problem actually originated with uninstalling Roxio software which messed up even more. That one will definitely not come back. Unfortunately our family iPods are useless without iTunes so that will have to stay.
I question myself sometimes whether I should consider iTunes itself a health threat to my PC. It installs extra processes that constantly run. It does not only slow my PC down during normal use, it also impacts boot time. I definitely belief that the same end result could be achieved through different and less invasive solutions, but maybe this is Apple’s way of telling people to buy a Mac.
To protect your PC against the evil outside world, you require much additional technology. A firewall and security software that checks your PC’s for any threat in so many different ways that your PC is basically not doing anything else anymore. But quite often you will check for the same thing many times over. These days many people will have a router installed at home to use the internet connection from different computers. Modern routers usually have a firewall included, but still Windows prefers to have its own firewall installed. Then, if you’re not careful, your security software will do the same thing. I know, you can control all this, but I do not expect the home user to understand or be aware of this. My mother definitely wouldn’t.
And what about scanning attachments of outgoing emails? If I make sure no bad stuff comes into my computer, would I scan again when I send something out? I may assume that the recipient has his security software up to date and if not, would it not be his problem? How many times should we check the same thing? But if you dare to turn even one security item off, you’ll constantly be warned that your computer is at risk.
You want to secure your PC because you don’t want to lose your data, your money or your valuable time. The only thing I know that if you secure your PC too much, you at least will have lost some money because your PC is more powerful than it would necessarily need to be. Or if you want to do something about that like me, you will have lost valuable time.
Besides the scare tactics by the respectable security software makers and Microsoft, I always have to smile again when I receive emails warning about security threats. Usually the only thing you lose is time reading and replying. I also love those websites that advertise a free PC scan. Just google iTuneshelpder.exe to find out not only how many issues that program has caused around the world but also that you should scan your PC for security threats.
In the end, the biggest threats usually originate from risky behaviour: downloading obscure software or visiting obscure websites. Or even worse, trusting people you don’t even know with important information.
These scare tactics are not much different than those commercials advocating people to use antibacterial hand soap for their children because they have been playing outside in the garden. Instead they should advertise to clean your mouse, keyboard and desk at work. According to the various google results, your office desk harbours more bacteria than the toilet. No wonder you feel so bad on Monday mornings.