MS Windows PC's are subject to receiving all kinds of univited stuff ranging from viruses, which hide in documents and other files which users knowingly import from reading e-mail attachments or inserting floppy disks or CD's made on other machines, to worms, "spyware", and "malware", which jump on the machine when users browse the Internet, without the users knowing it.
MS Windows machines need to be protected from viruses with the installation of virus scanner programs such as Norton Anti Virus, McAfee Virus Scan, or the free-or-low-cost alternative: AVG from Grisoft. The key is to make sure that your virus scanner is getting automatic updates of its virus definition files. If it is not, then it is quite worthless to be running it, since new viruses come out almost daily. If you pay for Norton or McAfee, make sure you have some reminder system to pay for another 6-months or 1-yr or updates.
MS Windows machines also need to be cleaned up from spyware and malware. When users go to some web sites, in addition to the pictures and text that comes down to your machine, which their browser asked for and displays, some additional stuff might be deposited on your machine and start up all the time without you knowing it. Ever see pop-ups just suddenly appear when you're not browsing the Internet? In addition, some programs which you download might install spyware when you install them. What does spyware do? Well some are seemingly harmless, while others are quite disruptive, earning the title "malware". At the least, they "phone home" and report on what web sites or pages you go to (spying). At the worst, they take control of your web browser and control where you go, or they run programs on your machine to be file sharing sites for illegal stuff, or they send out e-mail spam through you, or they signal a porn site to display dump pictures on your machine when you've started up the machine again (malware). Your machine can end up running very slowly because it's doing all the other hidden stuff. It can also be prevented from doing Windows Updates(where you obtain patches for security holes) So what can you do? Use anti-spyware programs.
Currently (3/24/04), the two best anti-spyware/malware programs are: Lavasoft's Ad-aware and ? Spybot Search and Destroy. Install and use them both. Why? They each get things that the other doesn't. As a result of walking around the Internet, your feet will get dirty. These two programs will wash your feet! Run them every so often (once a week or so). Spybot S&D has an "Immunize" feature, which you should use. Updates for both of these programs must be obtained manually which you should do before you run the scan. Also, BEWARE of imitations that call themselves something like "Spyware...", because they MAY be trojan horses - installing malware and even blocking the installation of real anti-spyware programs. There are other anti-spyware programs available that are good, but beware of installing something just because it has "Spyware" in the name or description!!!
The other thing you must do on a regular basis is obtain and install the MS Windows Updates. Security holes are found all the time for various kinds of computers on the Internet. Companies (or in the case of open source software "groups") are constantly having to fix their software to block access through exploiting those holes. Microsoft's Windows is the most prominent target. When Microsoft (finally) fixes these holes, they put out updates in a form called "patches", which can be downloaded and installed into your system. Now, Microsoft also puts out additional patches besides security patches, which is calls "Critical Updates", but make sure that you regularly go out and get the Windows Updates.
So, how do you obtain, install, and run these three things: adaware, spybot s&d, Windows Updates?
Instructions are here for installing/running these essential cleanup tools: