After having a major scare on my other laptop few months back, I have learned the art of regularly clearing my system of unwanted files and other applications. My other laptop is just 18 months old and I am very particular with its performance because that is where I do most of my blogging activities and have kept my important files. I make sure that I have done a Iolo.com pc tune up to avoid any untoward crashes.
I have now switched to a Mac but I am still maintaining the other one for the Windows' based programs which I don't want to install in my Macbook. I want my Mac free from any Windows-based software that may invite unwanted bugs, worms and other kinds of viruses.
It is advisable to do a regular or scheduled system and maintenance check to your PCs. Also update your anti-virus software to keep your PC virus-free. Get a legit license for your anti-virus so you are completely covered rather than downloading free trials which can only detect and quarantine certain viruses.
Be a vigilant PC user. It is wise to be cautious than sorry.