If you are a Windows operating system user then you will definitely come across virus infected programs from time to time. You will come across them more often if you make lots of downloads and also if you like to try out new programs(epecially the free ones).
You would also come across them if you have to crack a program using keygen or patches which are widely available on the internet.
I download programs a lot and I also like to try out and discover new and rare programs. Many times, I also have to get the crack of some program because I don't want to buy the product serial key/activation key ;-)