IT specialists use to say that the perfectly safe computer is the one that has never been connected to a network.
While I tend to agree, I must say that a few situations when a computer can get a virus even if it is not connected crossed my mind. For example, if you bring in and read a CD or a DVD which contains virused files, you may end up with your computer infected as well.
What files are mostly prone to spreding viruses? Without any doubt, exe files should never be run if you are not sure from where do they come from. Exe files are usually programs you install, so make sure you have them directly from the manufacturer. Don’t download any files from the internet, nor buy any CDs with pirate software. Besides the fact that it is illegal, you may end up with your computer having troubles, and even with major losses of data. So, if you want to use a software, the best way is to pay for it. How would you like it, if you were a software developer and people stole your work?
In cae you are not decided, qalmost all software producers offer trial periods and demo versions, so you can install one of those and see if that software actually does what you need.