I hear all these people with horror stories about their PCs and Windows programs, but I can honestly say that I do not have one. I keep up with the latest and best available anti-virus ware (for my money, I like Trend Micro Antivirus) and the best anti-spyware (I prefer Webroot Spysweeper), and run them fairly regularly.
I'm also very selective about where I peruse on the internet. At the risk of sounding like a prude, I urge those who have experienced problems to exercise discretion and personal fortitude regarding where they go browsing, i.e., KEEP AWAY FROM ADULT ENTERTAINMENT-ORIENTED WEBSITES.
So many of those adult sites originate outside U.S. borders in Eastern Europe, etc., and the inability to adequately regulate such sites in effect renders them the proverbial "Wild, Wild West" of the world-wide web. They are notorious for purposefully harboring and implanting viruses, spyware, and other noxious e-attachments that can collectively harm your computer's operation.